It's so hard when we find our message fall on deaf ears. I talk to people who love animals just as much as I do (or at least I think they do), and then I'll later hear things from these same people who make me just cringe. You can't say they were ignorant either, because I educated them!
My parents got two bullmastiff puppies in 1999 from what I now understand was a backyard breeder. They loved their dogs no doubt, but...I don't need to fill that in for you. The female passed away at FOUR years old from bloat in her sleep
(okay, probably not genetic), but at two years of age had already required hip surgery on both hips, and honestly was never quite the same again. The male (who eventually came to live with me after I graduated from college) required entropian eye surgery at around two years old while still living with my parents. I then had him for almost his last three years of life where I spent $20k (yes, you read that correctly, and no, especially right out of college I was not rich) trying to save his life, and he passed just shy of his 8th birthday.
Of course, you don't want to tell someone who just bought a puppy all of this and "rain on their parade" so to speak, but maybe THAT would have gotten the message across. Not only do you perpetuate the cycle of puppymills, but there is a good chance you will suffer while watching your pups suffer, and that is heartbreaking too.
Here is Hutch - the male (and yes, he has a pink teddy bear). And one with Starsky, and you can see Hutch is getting a belly rub in the background. I miss them both so much, and especially knowing that they went through so much pain breaks my heart.
Even the most well bred bullmastiffs still don't have a very long expected life span, so that makes it all the MORE important if nothing else can convince people...