Thanks for alarming about what is dangerous in promoting a site. There are many other black hat techniques in traffic generation. I prefer no to go with any such risky tasks.

Don't forget that linking back to a bad neighborhood will definitely affect your PR in a negative way.

Remember You have control on who you link to and not who link to you. That is why Google puts

Most of its weight on who you link to. So yes linking to spammy, porn, gambling sites that is not in your niche

Can affect you negatively with the search engines.