Well, I know in Yoshi's case that he's been well trained and well cared for by his previous owner, so I don't think it was a matter of not wanting him. Maybe the owner had to move and couldn't take him, or couldn't financially care for him any longer or something. But there is something to be said for people who just buy an animal, get bored with it, and throw it away. That's ridiculous.
But going to a shelter was always the plan. Not only were we giving an animal a home, but I knew it'd be a good lesson for Lily to learn. And, really, I'm all about not having to train a puppy not to pee in the house and chew the furniture.