For popular bookmarking sites like digg, they do not allow adult content isn't it? But what if I'm going to bookmark a thread in my forum that is not adult related, but some section of my forum contains adult material. Will they ban or disallow me for sending in this case?
No, they don't allow adult content. I think you'll probably be okay if you are bookmarking safe content from a non-adult oriented forum.
Ahh, that's different. I don't think I would risk that personally. If you get banned it's easy enough to get another Digg account - most of us are on our third or fourth!