This whole issue is psychological, not a matter of an insufficient tool kit. Think of all the debate over the true definition of a hacker. These folks are up for a challenge, and will look for a way to slip through filters.
Concerning moderation, there seem to be quite a few users that are annoyed. It behooves the powers that be to pay attention. As Natalie Portman's once and future daughter said,
...the more you tighten your grip, the more trolls will slip through your fingers...
...or something like that.