I can see where Sarah is coming from. On the other hand, when I was selling my house, and was under pressure for a quick sale because I had my eye on a new house, my estate agent and I only accepted bids from loan approved bidders who were willing to show their approval to the estate agent. This made sure that whoever's bid was accepted, that at least they would be in a position to close the deal . People do mess other people around. It happened to me in the past, where I accepted a bid, turned down another one just slightly under that, and the bidders that I had accepted, turned out to be wasting my time.
Hope this helps.