Common reasons for my downvote
Before I begin: I firmly believe that the net score of upvotes and downvotes is worthless as a measure of quality - I think at anywhere around +20, it becomes more a measure of catchiness, clickbait, and coincidence. However, I do think that individual votes have meaning as the aggregate of a single reader's opinion; and a novote doubly so: the mark of apathy. For me as a writer, receiving any vote i.e. having created an opinion is a success. A novote is failure. I like to know what my readers think of my work, and I also assume (until told otherwise!) that any given writer would like the same.
I don't really have any instant-downvote triggers, but there's a bunch of things that'll make me see your article in a negative light. These are guidelines that describe my opinions - they are not hard rules, and they definitely do not define my opinions.
Note that my rule is if it's in your page source, I can vote based on it.
Guidelines for most articles
Poor/lazy formatting: This probably applies to a good 70% of articles on the site, but if your article is just a page of text, I'm already looking at it in a negative light. If you couldn't take the time to make your page visually interesting, why should I take the time to read it? An image is a great way to break the monotony and get me invested without even having to make me read anything.
Caveat: Your formatting should match the content. A short, simple article should have simple formatting. A longer, more elaborate article can get away with a bit more 'just because I want to' formatting. Don't wear a top hat and a t-shirt.
Excluding people: The majority of the site's userbase is from the US, so when I see an article that assumes that I'm also in the US, as a UK resident, I immediately feel ostracised. For example, if you say "SCP-XXXX is located in North Carolina" without specifying "North Carolina, US", you're expecting that the person accessing this SCP document is in the US, and by extension the Foundation is US-only, and therefore as a UK reader, I don't count. Make your locations international and we're good.
Try not to exclude anyone, even unintentionally.
Lack of visual description: if you're telling me about something - be it an object, an action, a location, or literally anything - please please please describe it in detail. Visual description is the single most important thing to me when it comes to enjoying your article: I personally have to be able to see it in my mind to understand it properly. If you don't describe it, I'll assume things; and when you break those assumptions (which you will, because you don't know what they are), I get confused.
It's simple but easy to miss things - if your character walks into a coffee shop, I may assume that the cashier is on the right, and then get confused when you say your character talks to the cashier on the left. When you describe the room, specify that the cashier is on the left, and we're good.
Not making me feel something: there's a lot of very well-written articles out there that are just dull. You can tell an elegant, beautiful story, but if I don't come away from that having felt something or having had my opinion changed, the chance of getting an upvote is very slim. If I feel like my time has been wasted reading a series of words rather than a compelling story, there's a big chance I'll downvote.
A rating module at the end of the article: I firmly believe that ratings are meaningless as a measure of quality. So, by sticking another rating module at the end of your article, you're telling me not only that you disagree, but also that you don't trust me to remember to vote. If votes are so important to you, maybe you'll enjoy another.
Losing my interest: If I find myself not wanting to continue an article, I am not one of those people who thinks "well, I didn't read the whole thing, so I have no right to vote." I will.
Inivisible text: It's not 2014 anymore.
There are multiple valid interpretations: Now, I'm all for death of the author. In my opinion the only facts that are non-negotiably true for an article are those stated by that article itself. If an article is written, and it omits facts about itself - as arguably all stories do - then any reasonable interpretation of those facts to elicit the reality of the story is valid. For me, this happens by default. However, writing something and then specifically stating that there are multiple valid interpretations, or writing the article with this premise in mind, is a step backwards even from that. In the initial case there is a set of knowns and unknowns about the story, with the knowns carefully picked to imply whatever unknowns the author intends, but with other unknowns sneaking their way in like the story's seasoning. In the latter case, that line is blurred if it exists at all - all seasonings are added as if that mixture is a core ingredient. It can be perfectly edible and it can even taste good but it won't be the refined, restaurant-critic-worthy meal that the former could be. If I am reading something with, per the author, multiple valid interpretations, then I am reading a nebuluous mess that I will assume to lack meaning. In order to perceive a story as potentially holding meaning I need to at least believe that the author thinks that it does. If instead they say "the meaning is up to you to decide!", my default answer is nothing. Particularly if they then, outside of the context of that article's fiction, assert facts about it that the story itself does not include.
Guidelines for SCPs
Big headers telling me about a clearance level: Clearance levels are very rarely important to your SCP's narrative, and when you open with a big image that tells me I need level 4 clearance or whatever, my mindset immediately switches from "open to experiencing an interesting SCP" to pessimist mode. 99.9% of all SCPs have a clearance restriction, why does your SCP's clearance level need special attention? Use your big header to tell me about literally anything else - something I need to know immediately, important containment procedures that affect me as a reader, or use it to give context to your narrative.
SCP is a common object: If I could find the item that your SCP is based on in my house, you're on track for a downvote. If I feel at all that the origin of your SCP is "what could I make anomalous?" then your downvote is pretty much guaranteed. Equally, if you're telling me about an anomalous object but you're not telling about its origin, then that's a big weight on the downvote scale.
On the flipside, if your SCP is something unusual - like a concept, or a location, or something abstract, then I'm all ears.
The word "will": Compulsion effects for the sake of them are lazy writing. SCP-XXXX will do this, the subject will then do this, then X happens, then the SCP will do this. You've already lost my interest.
Testing testing testing: the Foundation contains. We're not Aperture Science - once you've done enough tests to establish the most effective way to contain something, stop.
Redaction: I explained my opinion better here, but the gist is don't redact anything unless you've clearly explained (or will clearly explain, later in the article) why it's being redacted. Redacted names of people and places is meaningless (just pick a name/a random place!), and redaction as a substitute for content ("SCP-XXXX then proceeded to [redacted]") can be an instant downvote.
Spooky notes at the end: There are so, so many articles that conclude with oooo a spooky note or a corrupted-text collapsible or something. Please just fuck off. Come up with something more original.
Breaking every unspoken rule: There are some articles that I instantly hate, but when it comes to justify that in writing, I can't do it. Sometimes I'll read an article, downvote it for eschewing some meta format without justifying itself, then think "well hang on… why is that a bad thing? Why shouldn't that article do that? Who says you need to stick to this unspoken standard?" This happens frequently enough that I am codifiyng it as a guideline: an article that makes me go through that process does not deserve to be instantly downvoted because of it.
This isn't an SCP: The articles on the site that get the most attention are SCPs. We all know it. It's not necessarily a bad thing. However, it's tempting for an author to want to optimise their article's rating by cramming the story they want to write into an SCP when it really shouldn't be. Sometimes it works - often it doesn't. When your SCP article stops being about the SCP, I know that you've tried to optimise my attention by posting your story to the most lucrative slot rather than where it should be. You can have written the most beautiful thing in the world, but if you're advertising that it's something that it's not, I will downvote it.
Guidelines for 001 proposals
I'll probably downvote it anyway: Inflation in 001 proposal numbers, especially with some authors making more than one proposal, has cheapened the once-valuable meaning of the format for me. As a result, my standards are so ridiculously high for 001s that a downvote is basically guaranteed. Amaze me. Any upvotes that I do give out are extremely volatile - if I read it and upvote, then I come back a month later and find that I'm not amazed any more, that upvote disappears.
Guidelines for joke articles
Joke articles have just one guideline. I ignore all the others - I'm expecting subtropes and parodies, after all. This is the only one that matters:
It's not funny: I upvote if I laughed and I downvote if I didn't. That's it. I'll leave a comment if I have anything more profound to say.
Guidelines for hubs
Not explaining what the hub is for: If I read your hub and I don't have a good idea of what I would need to write to contribute to it, you get a downvote. Otherwise you get an upvote.
