There doesn't seem much point in downvoting questions and answers that are deliberately offensive. Surely this is just drawing attention, which is probably what the troll wants.

I can't remember what the reputation requirement is for flagging questions as not welcome, but there are enough of us around that you can be sure an offensive post will be rapidly flagged.

It takes 15 reputation to be able to flag a post or comment.

For what it's worth, I don't think downvoting really draws attention to a post. It doesn't bump the question, for example. Downvoted answers are pushed to the bottom of the list in the default viewing order, and sufficiently downvoted questions (score of -3 I think, or perhaps -5) are prevented from showing up on the main page of the site. But of course the best thing to do is always to flag an offensive post as such.

• Well, if I were setting out to offend people a large number of downvotes would be evidence I had succeeded and therefore encouragement to continue ... – John Rennie Dec 31 '12 at 9:16
• I think "downvoting draws attention indeed" coz more users would be curious in finding what really the post says irrespective of the title by noticing a lot of downvotes. Still, we are men. We are too curious. Aren't we? A flag should be more than enough :-) – Waffle's Crazy Peanut Dec 31 '12 at 13:43
• @JohnRennie hm, I see your point, but I'm not sure I agree. In my view, extreme downvoting sends the message "we don't care about this." (except on meta) Or, if downvotes are taken as evidence that the troll has succeeded in offending people, I think the same could be said of deletion, or any other appropriate response we might take. Although I agree with your general point that there isn't much point downvoting things which are just going to get deleted anyway. – David Z Dec 31 '12 at 23:16
• @JohnRennie: /cc David Actually, this begs the question: do we really care about whether or not an offensive user gets any satisfaction? As long as the site is clean, it's fine :) – Manishearth Jan 3 '13 at 8:39
• @Manishearth I don't really care if they get satisfaction, not for its own sake, but if they do, it increases the chance they'll come back and continue trolling. That's something that would be nice to minimize. – David Z Jan 3 '13 at 8:40
• But then again, if someone enjoys getting their posts downvoted and deleted, what are we going to do, upvote them? :-P I think what really keeps most trolls coming back is when they get involved in arguments and visibly make other people angry. That's not what happens when we downvote. – David Z Jan 3 '13 at 8:43
• @DavidZaslavsky: I think what really keeps most trolls coming back is when they get involved in arguments and visibly make other people angry. Exactly my point. The troll will probably move their trolling efforts elsewhere if all they get are silent downvotes. (what's the fun in that?) – Manishearth Jan 3 '13 at 8:45

For one, IIRC a spam/offensive flag gives an auto downvote (this also happens if a q is closed as off topic, NC, NARQ I think)

With 6 spam/offensive flags, the post is locked, deleted, and the user loses 100 rep.

On sites where I don't moderate, I still downvote posts that I flag for deletion. I get the rep back later. I really didn't think about it as "the troll got attention". But you do have a point there :)

So I agree, a flag ought to be enough.

A note: as a 10k user, you can see most flags and counterflag them here. (you'll get a little yellow bubble on your topbar when the number of flags exceeds 5)

• I didn't think any sort of flag gives an auto-downvote. But I could be wrong. – David Z Dec 31 '12 at 8:46
• Yes, every spam/offensive flags counts as a downvote from community. So if you flag and downvote, you get to downvote the same post twice. – Mad Scientist Dec 31 '12 at 9:57

I'm sure the examples you have in mind are offensive and there isn't much question, but it still helps to downvote and flag because a flag could be rejected and then your downvote is still important. You're still saying you don't think the question is a good one or belongs, which is why votes exists.

So I like to do both in case a flag is rejected. I still get to express my opinion on the question quality.