There is already a thread discussing this. This issue has been addressed as follows:

As for ads, we block domains like dating site and other potentially harmful [such as to women or children-involved] ads. If you spot one, please click the ad to see the domain name [eg chinesewomendate.com] and send it to us using the Contact & Support links at the bottom of any page so that we can be alerted and block them.
Once again if you prefer not to see ads we offer a solution.