I test after I pay and test in front of the salesperson. I tell him/her that is what I am going to do and he has to replace if something is wrong. Is that fair enough?
I dont try for the sake of trying - I try to make sure I am not getting a lemon.
If you want to try before you buy, go try at some shop who like you to try.
By the way I dont need to try at the shop.

I can go to service center and play.