It's something I see quite a lot on Mumsnet. I'm including my own job here: I'm a lecturer. I work hard and I think I do a good job. Several times on Mumsnet I've seen threads about problems DC are having at university, and lecturers posting along the lines of "that could never happen" / "a lecturer would never do that!" Meanwhile I'm thinking I've definitely worked with people I could imagine doing that!
It seems to be the same with a lot of public facing roles on here, e.g. teachers, doctors, receptionists, call handlers. I'd understand if a poster was complaining about all of your profession, but if someone's posting about a specific incident, why do posters automatically disbelieve them? Do you really think everyone with the same job as you is good at that job? If so you must have been very lucky with your colleagues!