Depends on the retailer.
DC actually likes when window shoppers come in and crease a bunch of pairs of pristine shoes, so that they can piss off their paying customers by sending them creased shoes
Ralph at NYC gets really pissed off. The other guys that work there don't mind as much
Steven at Leffot asks that you don't crease the shoes while trying them on.
Alden SF is pretty accommodating, somewhere in the middle of the spectrum.
so excited about my trip to alden dc now.