I don't think Google has a bias against linking to porn sites.
But your customers might.
Unless yours is an adult site, I would recommend not adding Adult Site links. There are lots of 'related' content sites to exchange with that would actually boost your google rank due to their relevancy to your content.
But if your site is adult related, go for it. And with names like
HornyMatches and
SexDatePersonals you should see what else they are interested in trading.
- Marketing Guru