As someone who is active in the gambling boards and have a few threads there that I maintain, I can safely say that the worst kind of posts I see are those made by 1xBit participants. It's not just the fact that some of them can't write a single grammatically correct sentence, but some posts literally make no sense. And 9 out of 10 times when I come across those, there is a 1xBit signature underneath. It's hard for me to say if all of them are serial spammers, but the majority is.