As a young trainee salesperson on a static caravan park, I once gave a rough looking family who turned up in a rusty Transit short shrift as I considered them a waste of time when they wanted to look at the most expensive £35K models on the premium pitches.
My manager gave me a massive bollocking and went out into the car park to talk to them before they left. He brought them back in and then went on to sell them the most expensive van on the best site on the park.
To further humiliate me, he made me sit in on the proceedings and taught me a very valuable lesson which I have never forgotten!
He collected a nice wad of commission that day, that should have been mine, and after that some of my best sales came from those who looked like they were on the bones of their arse!
Those who turned up in a flash car, wearing designer clothes and talking the talk, were often the waste of time, as they usually wanted to buy on finance which was invariably declined!