Do you also get those annoying Pidgin Spam over your ICQ client and your Messaging Protocols? Most of them are Russian Bots. I discovered a very effective method to block those bots now: The Pidgin Plugin BOT SENTRY.

INSTALLATION

Download bot-sentry-x.x.x.tar.bz2 and untar it.
Im using Ubuntu 10.10 with build-essentials installed. I also needed to install the intltool and libpurple-dev packages. Run sudo apt install build-essentials intltool libpurple-dev if you're unsure whether or not you have this packages installed.
run ./configure; make; make install in your bot-sentry dir.
By now you should have a new Plugin in your Pidgin Client
You might want to change the default question, just in case there are bots out there who knows the answer to that.