^^ they will expect you (and drugs take a while to kick in anyways). If you really want to know whats up show up even an hour before just drive by and see the place -- you can tell A LOT by the way their property looks -- and then go have lunch or whatever before the scheduled time.
Also I never handled horses at all before I saw the owner do it, not even lead them out of the paddock, not only is this good for safety concerns but also to see if the horse looks lame.
Most sellers will not let you do a trial period do not be turned off or offended by this simply understand that they are just as concerned with you and the horse being a match as you.
Also I didn't get a PPE because my trainer has 30+ yrs of experience and can count on one hand the horses she has had go chronically lame. AND as many horse owners know horses can hurt themselves any number of ways, a PPE is only an exam for that day not what will happen tomorrow
Finally most important NEVER GET ON A HORSE YOU AREN'T COMFORTABLE WITH
"I don't think he ever gave a thought to other people's opinions, which was just as well because they were often unkind."
-- James Herriot, All Creatures Great and Small