As a moderator I see a lot of flags for "very low quality". Sometimes they can be fixed. A lot of the time the flag is code for, "this is a crap answer," and nothing can be done but down-vote it, delete it, or ignore it.
Based on the consensus of the flaggers, the community as a whole appears to want these answers expunged from existence rather than downvoted to irrelevance. Sometimes I handle such flags by downvoting them myself and dismissing the flag as helpful. I know I can afford the -1 rep for a downvote like that, so I do so.
I'm curious about the consensus of those who don't routinely flag. Is it better for bad answers to be quietly disappeared where they can do no harm to anyone, or is it better to downvote them severely to demonstrate the community's disdain for such behavior?
Note, there is a difference between bad answers and actively harmful answers. Bad answers can be as simple as link-and-run answers to more complex ones where the answerer clearly misread the question and answers the wrong point.