20 years ago I had a horse up for sale, he was an extremely talented jumper an absolutely loved jumping and competing (but he was bolshey and too strong for me to handle). I was selling him from professional yard with full facilities and had a man come to look at him as a prospective buyer.
The man said that he was really interested but would need to do the following during the visit to make sure the horse was right for him: hack out on and off road, SJ indoors and outdoors and ride around the x-country course (old Novice level). I agreed thinking at least he was being thorough and hopefully it meant if he bought the horse the horse would be likely to stay with him.
The viewing took HOURS and the horse behaved impeccably and jumped like a star (the man was a lot stronger than me so much better at handling the horse and had no trouble). When he dismounted at the end of the viewing and I said 'do you think you'd like him' he said that the horse was perfect except he wanted a black one and would never buy a chestnut, so it was a no! The horse's advert had a picture, and he was described as a chestnut in the wording, and clearly couldn't be mistaken for a black- I was fuming!
Ironically the man actually did me a favour; as a result of me getting so cross about the viewing I took him off the market, a few weeks later his bolsheyness completely disappeared and he ended up as my horse of a lifetime until he died 20yrs later. The man missed out on a bloody good horse, but I suspect he wasn't interested in buying anything and just having a free ride.
I haven't tried to sell a horse since!