I have a dog who is a massive Labrador cross. He's huge and a lot of people are a bit startled by him when they first meet him, but pretty much everyone then decides he's their favourite dog. He's fairly well behaved but I think the reason is because he has an incredibly expressive face. He smiles, he looks searchingly at you, he can even look skeptical or quizzically at you, and the look of excitement or hope when he thinks he's about to get a biscuit.... It's hilarious and completely gorgeous. My other dog is very sweet but you cannot discern his expressions at all.
Do your dogs make expressions? How true are they to how they're behaving or feeling at the time? Do you agree that it's the most adorable thing ever? 