This, and I also think that the general pet dog market (BYBs, puppy mills) really does see a higher demand for small dogs. Not that all little dogs are poorly bred, I just see way more "I bought it from a pet store" Chihuahuas, Yorkies and Shihs. I personally adore small dogs- and I meet a lot of nice small dogs too. Actually, after working at a grooming shop, I changed my mind on Shih Tzus. I used to really dislike the breed, but I meet so many nice ones. The thing is, if my BC jumps on someone, it is a problem. If a Great Dane jumped on someone, it could cause injury. If a Pom jumps on someone, its annoying. You also have to keep in mind the average, run of the mill pet owner will only train their dog if there is a specific problem that needs to be fixed, and like I said, a bigger dog can be a liability if it isn't well behaved.