I don't let Aurora walk on the floor in those stores, so she doesn't leave messes in there. I seen too many dogs that looked sick and way too many dried messes on the floor, to let her walk. She stays in my arms or in her stroller.
I get very grossed out because everytime I am at the local petco, there is dried pee and poo on the floors. Sometimes same dried spots are still there on the next trip.
I no longer go there unless I really need to.