I used to have a problem with people flaking out on deals, which is a piss off, especially if I had other interested people whom I turned down because I was waiting on someone and then are no longer interested when I contact them again.
Now my rule is, first one pays get's it. I don't hold anything for anybody unless you want to pay a non-refundable deposit. You flake out, you lose your deposit. Simple as that. Since then, have not had a problem.
If I was banging all of them, I'd be a manwhore. At the moment, I'm just an opportunist.