I prefer that a relatively well worded but completely wrong answer remain but be downvoted so that future readers know that it is a Bad Thing. The more comments on the answer that explain why it's bad, the better.

I only flag answers that are:

 1. Obviously shilling for a product.
 2. Completely unintelligible.
 3. "Me too!"
 4. Asking a question of the poster.
 5. And sometimes: is so hideously formatted that it would take more than 15 minutes to correct.

 



Keeping bad answers around for posterity is a Good Thing.