Large furry mammals, the kind that they use in lab experiments. Not the kind that sneak in in the middle of the night either. Bread would be delivered into a prep room and you were told to put the trays up on a table in the middle of the room to keep them off of it. When you enter the room they would be sitting on the pipes along the wall and they wouldn't even budge. As soon as the bread was placed on the table and you back away they would start jumping off of the wall and attacking the bread. Invariably the ""restaurant"" would call the bakery and complain that the bread had evidence of these guys gnawing on the packaging and leaving there excrement behind. Meanwhile the bakery was a world class Kosher operation where I never saw one in the many years that I was there.
Pros: Couldn't say, wouldn't eat there
Cons: The fact that they ever managed to stay open