Hypothetical situtation. I am trying a horse for sale. Seller rides horse. I decide I do not want horse. Do I get on and ride anyway?
Anything is Possible: I could change my mind. Highly unlikely, particularly if the horse has physical issues, but theoretically possible.
Learning: It would be good practice for me in evaluating strange horses.
Counterphobia: One should do the things that make one nervous.
Bad Manners: Definitely not if the horse is thundering around the ring doing his impression of the Oncoming Storm.
Exertion: More work for the horse, especially in heat, cold, rain.
Liability: What if something happens while I ride? What if nothing happens and the horse comes up lame for another reason entirely & I get blamed? Granted this is an accepted risk of showing &/or trying a horse, but why expose myself/the horse if it is not necessary?
False Pretenses: Good practice for me is just using someone else’s horse for my own ends. (Update: and wasting the seller’s time.)
Ride or not?