So I reported this spam thread, but I noticed that it came from a user that hasn't posted here since 2009. Most spam threads come from users with only a few posts, and this guy had about 350. I took a look at his previous posts, and for about five pages of posts, they're all about music. So maybe after 5 years, this guy decides he's suddenly going to come back and post sex spam. I wonder though if instead a spammer is finding inactive accounts and cracking weak passwords.
I think I know which one you're talking about because I saw a bunch of strange posts but didn't even know if they were spam or not.
The one I'm thinking about is underage porn spam. I don't think I've seen spam from a hijacked account before.