Itβs a dick move to pinch leaves if for no other reason that someone else may want to buy that plant, and youβre damaging it. Enough people do it, itβs a dead plant.
Leaves fallen to the floor? Boutique or not, fair game. If youβre willing to propagate from a leaf, youβre probably not going to be buying whole plants anyway, and it doesnβt hurt the store.