If you've ever tried selling a car privately, and had your time wasted repeatedly by flakey buyers who don't show up when they say they will without calling, or put in an offer on the car to never be heard from again, and generally waste your time, then you'd be able to see things from the other side as well. Selling a car is not a hobby, cash in hand is what you're looking for. It takes a lot of time to have a car clean inside and out and ready to show a prospective buyer, and people have no respect for your time.
It sucks that you had made arrangements to view it and it sold before you got over there, but unless you had a deposit on it, the car was still actively for sale. Lesson learned. Hope you find the one you're looking for.