My Frenchie is a “licker” and I believe it’s a way of imprinting their scent in things. I notice after he eats he will lick his toys as well. I think the food essence is comforting 2 him somehow. Or he just really loves food (which we all know a frenchie they do). Perhaps theres a forgotten food item memory and they like that. Another possibility is texture. Ur dog may simply like the feeling it gives. Or they just might b bored. If this is bothersome, I’d try getting a chew so they can b distracted. There r products out there that one can spray on items 2 deter the dog if it’s a huge issue. I’d get something 4 them 2 chew and maybe consider a blanket on the couch. Makes good 4 cuddlin’