The bad news is that you’re attracting the wrong kind of attention. And the last thing you want is to offend your REAL audience with shady or off-colour or downright nasty comments that unscrupulous attackers are sending your way.
I’ve tested a number of spam-prevention methods and plugins, and the one I like best is Akismet by Automattic. Akismet filters out your comment and track-back spam for you, so you can focus on more important things. There’s a good description here on how it works. (And how can you not like a plugin from a company that writes its product descriptions in haiku?
It costs all of $5 US per month per site. For the price of a latte, protect yourself!