I'm thinking you're thinking along the right lines. Appart from anything whatsoever to do with AO-Hell, AIM client applications are notorious vectors for yuckware infestation, perhaps second only to P2P apps. Making the rounds of AIM-lessness right now are a variety of
Rootkits, along with a few very-difficult-to-detect-defeat-and-remove otherwise conventional virii and trojans.
Getting rid of these infections, reversing their effects, and excising AOL from your machine often is an exceedingly irritating, tedious project.