Recently, there have been several individuals posting and announcing/discussin kinks which, at least in the US, are illegal. There have been specific posters expressing interest in "young" women and in sex with animals. Given that the US government employs people to search the internet looking for just these things, and adveratising it on a forum will draw their attention while they wait for you to download illegal pictures so they can pounce, why adveratise? Your internet self is not untraceable.

I suppose I was wondering about motivation, and whether you ( the posters in question or anyone else) is concerned about what the athourities might find out about you.