Spam on Twitter

Still Twitter shows me surprises every day, I managed to have my tweets transported to my blog on Livejournal and still working on Twitterfeed to work. This should transport blog entries to Twitter. I am still curious why I follow some people who don’t follow me and people who do follow me but I don’t know. But besides that, today three people added me to their list but when I check them they have weird arbitrary usernames and no other users follow them. The three ‘users’ are darcyxl6hu, yasukocibz and shaezi9stx and I already blocked two of them. On their userpages there’s just one tweet with an url that invites me to register on Perfspot.com. It looks like some kind of Social Network Site to me. Maybe I should register and check it out? This website doesn’t let go of me though, when I try to close my browser window I get a pop-up saying some girl wants to chat with me. The question is, why did these users follow me and why today? What keyword did I use today or before that triggered them to follow me? Do other users have this kind of spam too? I did check the other real users that are being followed by these bots (that’s what I think they are) but didn’t find any keywords that match mine.