Re: The problem I have so far...
I think a lot of downvoters are particularly rabid fanbois. In an article saying bad things about a particular OS, some fanboi will take on the task of downvoting every comment that also says bad things about that OS. At least until they get bored and move onto the next article.
I suspect the next biggest group is prudes, downvoting anything that'll trigger a prude. Prudes hate it when other people enjoy themselves doing things you are not allowed to do in public, and it's the prudes that are the reason why we are not allowed to do these things in public in the first place. Typically if you scratch a prude, you'll find underneath is someone that does one or more of these things they hate others doing, but wont ever admit it. It irks them that some are quite happy to talk about these things in public.
Then there are shills, I'm not sure how rampant that is here.
Finally, there are the randoms that will downvote people pointing out that the sky is blue, or humour impaired randoms that just didn't get the joke, even if there's a joke icon.
Personally I'm generous with my upvotes. Due to the fact that up/down votes for ACs are not counted anyway, I'm getting into the habit of just not voting for them at all*. The only things downvotes are good for is sorting comments by popularity, which I never do. Given all of the above, popularity is screwed anyway. Upvotes are good for earning your silver badge, but you have an entire year to get there if that's important to you, gotta get your bronze first. I'm about six months into my first year, I have plenty of upvotes, I'll skip right over bronze and get silver in late December. I'm considering being very helpful for the next six months, if I'm lucky I might skip silver as well and go straight to gold. A mans gotta have goals. B-)
* I have noticed there is someone with the account name "Anonymous Coward", who has a badge, so we can easily tell them apart from the actual ACs. I'll give that person votes.