Used to describe a homley, funny looking pet; usually a doggy or pussycat that is so ugly it's actually cute. You tend to feel sorry for this critter. The runt of the litter. Bull dogs, pugs, chihuahuas, manx and hairless cats come to mind.
Mr. Bigglesworth the hairless pussy cat in Austin Powers looked so freakish you couldn't help but go awww, he's so ugly cute.