How can you quickly tell if there are kids in the house even before you get to meet them? That's easy. Check out the walls and doors for some tell-tale signs.
Stickers and more stickers of their favorite cartoon character - makes me wonder sometimes why they are so fond of them, as if I haven't passed that stage once. My mother-in-law has 3 grandkids of different ages. And this is how their door looks like now upon entering the house. :-)