I used to have contacts at race training stables who would call me when they had a reject that they didn't want to go to slaughter. 90% of their rejects went to local auctions. I have no idea who was buying them. The 10% that we saved were retrained to be show horses. Every single one of them did well.

On another note, only one mare out of the hundreds of horses going through the program was a bucker. She was kicked out of race training because she would buck the jockeys off if they whipped her. She had won a few races, but they were sick of dealing with her and didn't want to breed for ornery. I kept her for myself and she was a kickass Dressage horse.