Every single one of my dogs is fit. But we've had people call animal control on us because they say we're neglecting them and not feeding them. Of course all these people have obese dogs. That's the thing. Just like people, so many of of today's pets are overweight. People are so used to seeing fat dogs that they think fit ones are too skinny, that fat dogs are fit and that morbidly obese dogs are just a little chunky.
Plus, I don't know what kind of dogs your mom has, but different dogs have different body typs and so they look more thin/fat than they're supposed to when compared the breed you're used to. Like Araby and Sanity are both deep chested dogs, with tiny little waists. When compared to Hobo, who's a working barrel chested dog, he looks fat. In fact we call him Chunks, even though he's really not. Put a muscular Rottie next to a muscular natural eared Dobie and 80% of the population would say that one is fat and one is thin.
Ang