I struggled with this issue, the selling part, not the rearing. My gelding is a great horse when rode by a confident rider, if your like me, low confidence and if
He spooks you end up on the ground lol So when I decided to sell him I went over all of it with my husband and he looked at me like I was crazy. He said when you sell your horse, your selling your rights to that horse as well, and your just asking to be lied to, by the buyer. I listed my horse and I made sure that I was very honest about him and when the buyer came I went over all of his faults, probably more so then his attributes. I didn't get a lot of responses at first, but finally a girl came out got right on him and rode him and he looked awesome under her hands. He is hers now and I'm very happy with it.
On a side note my friend bought a buckskin, she even rode him and our friend rode him as well, so she bought him. She got him home and the next thing you know he started rearing, not just once but everytime she got on him. This horse was her first purchase and her first fall from a horse. It was very dissappointing for her and luckily we had a friend who worked with her and the horse and now she rides him and isn't afraid of him. She has learned to recognise the signs of when he might potentially rear, and get him through it. I don't think it would have been fair to her to have to keep this horse if she hadn't been so lucky to have someone to help her.