I think they are actually "Plain Clothes" cats who are on a "deep-deep" undercover surveillance mission. You
think they are asleep but noooooo...they're waiting. Just waiting. Any moment now something edible will drop on the floor and they will pounce on it and make an errrr... an ARREST! And confiscate the evidence! Yes, that's it ~ they're "on the job". We can all rest easy now...