Why do pitbulls continue to be demonized?

My poor pup has a bad UTI, I took him to the vet for care. The vet praised him for being so behaved, he greeted cats that were nervous about their appt. No hissing from the murder mittens, and no negative behavior from him. This couple came in with a small ankle-biter; they took one look at my pittie and scooped up their dog. They then said 'This isn't going to be good." while looking at me. My pup was nowhere near them. 😔