I sell somewhere between 5 - 10 horses a year. I am a breeder, but have ended up doing consignments for others. I also buy a few from time to time.
A prospective buyer can ask all the questions she wants. I have filled out questionnaire, I have answered everything about health, horsekeeping, training, behavior, etc. I still believe it comes down to whether the buyer is happy riding or driving that horse. If the horse can do what you want here and now, the fit seems good after multiple visits, and the PPE shows nothing, then it’s likely to be a good choice. And definitely always have you vet draw and hold blood at the PPE. I actually request it at the PPE as it protects me as a seller!
I have learned from my own journey with horses, that there can be a disparity in what buyers want and what they can do. Personally I want a good match because the horse’s future depends on its success with the new owner. I am lucky to have 135 acres, so I have room to keep a horse indefinitely.
Shopping can take time, but I think that there is an appropriate horse out there for most people.