Unfortunately, I have heard all these excuses and more when volunteering at shelters.
I wish more people would adopt rather than buy. A lot of ppl convince themselves that the animals in shelters will find homes, but sadly that isn't the case. Here over 30 dog per WEEK are killed and only about 10 are adopted or go to rescues.
Many ppl are convince that their arent any purebreds in shelters, or all shelter animals have issues, but again, that couldn't be further from the truth. I have never bought an animal, but yet I've been lucky enough to own a purebred Bichon (owners moved off and left to fend for herself), a purebred lab, a yorkie/chi mix (turned in b/c she was a door bolter), a yorkie/poodle mix, and a couple mutties.
I have also fostered (all came from shelter) a purebred poodle pup, a 4 lb adult poodle, a purebred chi, a JRT/poodle mix, a boxer mix, and a basenji mix. GREAT dogs can be found at the shelter!