My attack on spam members

[LynnB]

I'm in the process of deleting all accounts that have spammy html in the profile. I also have new registrants requiring admin approval. One thing still puzzles me greatly. I have a lot of members who have no website listed and no signature. But I see them being logged in. They have never posted and while I don't think they are legitimate members, I would like to know what it is they are accomplishing by logging on before deleting them. What am I missing here?