Nate, it depends on each customer. Most put their hands over their eyes/face which can smudge or wrinkle them. Some glasses will fall off onto the floor when reacting from a good scare and may get stepped on if not picked up.
I guess it depends on how effective your haunt is.
They aren't made to be re-usable but you may be able to salvage some.
I used the plastic framed ones which can be cleaned and/or repaired and used over and over again.