Well, they can always avoid the obvious and hope the lease doesn’t include such things as “reptiles, amphibians, dragonets, guard lizards and tame Dungeon Dwellers.”
Hopefully, the above-mentioned critters will have hatched and gone on to bigger and better things before the landord/lady is even aware that the building(s) is even inhabited by such things.
Hopefully.
My landlord brings his little terrier along to enforce his “NO DOGS ALLOWED” edict.