I am sure we all get bugged by trolls. I would like to avoid having to moderate every post, and one suggestion made to me was to disemvowel the unacceptable posts – which makes the point nicely about what is acceptabler and what isn’t. There are scriots that can be run on wordpress – but not on wordpress.com.
I use the Options blacklist to hold comments from certain people for moderation–that way I at least get to see them before they show up.
I have had an ongoing problem with white supremacists on my blog. While I want them to be able to show just what [insert swear word of your choice] they are, I don’t want them to use certain words or to link to their sites.