There are no ways of telling. When I was selling my last car a young guy phoned who seemed really keen. It was going to be his first Impreza, and first performance car for that matter. It had been my first quick car too, and I had spent about £4k getting it exactly how I wanted it so I obviously wanted it to go to someone who would look after it. I certainly wasn't in a rush to sell it, so when he told me that buying my car would depend on the sale of his, I told him I would hold on to it for a few weeks.
He kept me updated with texts etc for the first week and then I didn't hear another thing. He seemed really genuine and a nice guy too. I had told a few people who phoned in that time that the car was sold!
I was obviously being soft at the time, but as I said, I was sort of attached to that car.