I've been on SB for a few years and had a varying amount of success in the region. As other have said it is easy to burn through the credits as opening a message is 10 credits, private pics, message boosts, etc. Plus they do this really annoying thing of sending a request to view private pics with every message you send.
My MO is to chat first and see if there is a connection, before looking at the private pics.
There are decent genuine girls on SB, but there are also a lot of the pic sellers, online only brigade.