I'm much more an answerer than an asker.
It's interesting to see how many people research the answers; why not just do that from the start? (I suspect you've got a very unrepresentative sample of participants here.)
I am alarmed, however, to see how many people use Best Answers previously given as a criterion. From my experience here, "Best" is a misnomer much of the time, and a lot of people cheat. And a lot of people get high percents in some of the lamer categories.
Most of the time I answer, I read the whole question to make sure I'm answering what they want to know.
I try to be complete in my answers, and usually explain WHY I say what I say.
There are a lot of different kinds of questions here: facty ones, advicey ones, "make this intelligible to me" ones, and all kinds of non-questions as well.
The kinds of answers, and criteria for judging, then, are also varied.
I would think that if you're judging reliability, you're looking for things that make sense, given what you already know or think.
Sometimes you can tell when people know what they're talking about, as their answer makes sense, hangs together well, uses reasonable and moderated language.
Answers that respect the complexity of things seem better to me, than the absolutist stuff (usually).
I've seen questions here disputing the very notion of this site: If you don't know, it's impossible to know which is correct; if you're asking for opinion, you just want someone to agree with you.
These are both wrong, as often you CAN tell which answers are most plausible.
Also, I often disagree yet get picked Best because I explained my answer, and showed I understood the asker's perspective.
Giving balanced answers helps here, for some askers.
I've had quite of few people comment when choosing me "never thought of that."
Though sometimes people pick a Best because they disagree and want to leave nasty comments. This cracks me up, as people coming upon the question later, through searching or browsing, then see this opposing view on top, label led Best.
But it's like any other reading. Sometimes the sanity of the person is just apparent in what they say and how they say it.
There are a lot of people who post completely false "facts" though.
It's all very tricky; but very interesting, no?