I used to do that. But when I did it, was always because I didn't want to foster a relationship with someone while my mind was still on someone else. It wouldn't have been fair to the girl that I really wasn't interested in. Once the girl started to give up on me, I had to let her go.

Likewise, if you really aren't interested, you need to let them go. Don't collect "potentials" and juggle them. Unless you fancy yourself as a 'playa'. But real love seldom comes to playas.

In my opinion!