There's a user who frequents the same tag as I do on Stack Overflow, and I consistently see him giving either bad advice, or advice that's not relevant to the question or just says "no you're doing it all wrong, do this instead" where the this is not best practice. It's not the worst, but it's far from good.
Unfortunately the tag I frequent doesn't get much voting traffic (and generally has a lot of new users, some of whom don't know the difference between a good answer and this person's answers and some of whom don't vote or mark answered) so I can't just post a competing answer and expect the community to magically solve the issue of the other user's answer quality. Plus I don't always have time to write a better/more-detailed answer, and sometimes I don't have enough confidence in my domain knowledge to propose an answer (though I know that this other user is at least somewhat wrong/bad).
My question is - what do I do in this situation? Once or twice I've voted this user's answers down when they've been particularly bad. Earlier today I commented on one of his answers saying that it didn't really answer the question asked (as well as posting my own answer giving a really detailed discussion of what can be done) and got a snarky "well I could give all the details like you did but then he's not learning" response back (I admit maybe I went over the top and gave an almost copy-and-pastable answer, but this guy's answer was completely rubbish and did not answer the question).
There doesn't seem to be a way to flag a user for an in-depth moderator overview, and I'd rather not waste the smallish rep I have (600ish) downvoting 90% of this person's answers.
I'm really new to SO myself (only because particularly active a couple of weeks ago) so I don't know the conventions or whether I'm caring too much. Any advice would be appreciated. I can give concrete details on request (examples and explanations of the user's bad answers, the snarky comment to me (which I flagged as non-constructive, by the way)) but thought I'd ask in the abstract first.
FYI the user is not a troll, but I feel that they think they know more than they do. They're probably trying to be helpful like most of us here, but the majority of their answers are just plain bad/confusing. They probably don't even realise it. However, it appears that they take criticism badly, and I certainly don't want to go around commenting on all the answer I find bad explaining why, especially when I have lower rep than they do.
Slightly related: How to handle accepted bad answers?