
Hi Debbie,
I'm not a specialist in bullmastiffs, but it sounds as though your pup is a 'purely-pet' quality example. I don't mean that to sound demeaning or disparaging in any way - in all litters there are 'good' pups and 'not-so-good' ones when it comes to the breed ideal of perfection. From what you say she is a purebred, pedigreed bullmastiff, so I wouldn't worry that you have been conned. Her breeders have said why it wouldn't be worth showing (or breeding from) her, because of the lack of dark muzzle, and her coat length etc, though when she changes her puppy coat for hr adult one that may improve.
Love her as your pet, and she'll be a very lucky dog!