It is not worth the trouble. You will get emotionally messed up. When you help someone "settle" down, there are usually a few strings attached. That will screw up your happiness.
Fact is that most of these girls get addicted to the "quick" money and the lifestyle (drugs / booze etc). They know that they can earn a month's wages by sleeping around a couple of times within a week and hence lose the motivation to work a normal job. There are exceptions of course. There are girls who, given a chance, would settle for a so-called "normal" life. But they are in a minority... few and far between.
Some guys/girls enjoy sex more when there is an emotional connection. It is okay to "connect" with them only to the extent that your sessions become more fun. But there is no point in getting emotionally involved. It is best to remember that you are paying the girl to leave. If you are the type of guy who tends to get emotionally attached to chicks you bang, then you should refrain from repeat sessions with the same chick... OR get a few more girls into the rotation so that you don't get involved with one particular chick.
Don't think about "saving" or "rehabilitating" any of these chicks. That is a slippery slope and will likely lead to your downfall. Bang them with all the "temporary love" and respect you can muster during the session.