Would you happen to be using iChat? I find iChat to be weird sometimes, and not show all buddies (including those pesky AIM bots). You can use AIM Express (Web IM - AIM Express) in any desktop browser (sorry, doesn't work with the Pre's browser - I tried!) to remove them.
ya...thats what i did...didnt work on ichat, went to aim express, deleted them, deleted the account in messaging on the pre, then reentered account info, and the ones like smarterchild from when i was like 15 are gone..