Y’know, I was going to say something about the vitriol implied by the OP’s choice of word, but given the nature of the communications, “whore” probably is reasonably accurate. Although “pimp” would probably be even more so, since the person responsible for sending the messages (that is to say, the person who started the inhuman script that’s actually doing the sending) is almost certainly not the woman (if any) who is depicted in the pictures (if any).
I will also say that I’ve never gotten any spam on AIM, but I have received messages from people with whom I had no prior AIM contact (mostly other Dopers), so I know that it’s possible for messages to reach me without being explicitly authorized. I don’t know what distinguishes my situation from that of the OP, however… Maybe I’m just lucky.