I've never had a problem, never been flaked on, never been scammed. It's not so much a needle in a haystack as a trip to the candy store.
I probably go on 1.5 meet and greets for each established arrangement.
The key is the aggressive use of filters and vetting, rapid and clear communication, communicating ones expectations and offerings prior to the meet and greet, the use of the platonic meet and greet to establish chemistry rather than negotiate terms, and honest and earnest communication thereafter.
I will say that I only date older (>25) and better educated (>Bachelor's degree) SBs. That alone cuts down significantly on drama.