Yes you can use them, All popular and successful dating sites want more and more members, get them from search engines, internet and media and other ways is very expensive and sometimes spend more money when give back results.
The most easy way is to exchange profiles between dating sites and social network sites.
This is a popular way and websites do it very often directly between each other, and many times they use our company, which acts like a broker. We take profiles from several dating sites and exchange them with these sites without payments. As broker we allowed use these profiles when selling to a third-party.
Popular dating sites managers and owners never sell their profiles because there is no point in making millions of dollars from dating sites and then sell profiles for only a few hundreds dollars. So, to get real and active profiles for low price it is only possible from exchanging the profiles from popular dating websites.
We have been in this business almost 10 years. We are pioneers in this business and we know many popular dating sites top managers personally and we deal directly with them.