Forgive the 'user' name. Didn't want to be identified so went NC.
I also get royally pissed off with people not believing too.
Earlier this year, our daughter painted an amazing Star Wars pic for DH's birthday, and it was excellent (she did Art A level and is very good.) DH photographed it and put it on facebook. When he got back to work, he took it to show people, and several people didn't believe she had done it, saying it's 'obviously' a professional pic. DD was flattered saying 'wow it MUST be good!' But it annoyed me a bit.
Then a few months ago, DH acquired a really good camera, and has taken some great photos of birds of prey, foxes, the sun, the moon, and the mountains that are 20 miles from us as the crow flies, amongst some other things.
When he put them on facebook, one woman said 'great pics PMSL.' DH said 'what do you mean PMSL?' She didn't answer. Next day at work, long story short, she didn't believe he has taken the photos, saying they were 'too professional.' He was a bit taken aback but also a bit flattered. But she has done it several times since. She keeps questioning how they can be so clear and professional looking.
I am getting really pissed off with it now. I said to him 'she obviously isn't intelligent enough to realise that people who are not professionals, can still take good photos with a good camera.' I mean why not just call him a liar? That's what she is virtually doing.
Then there are other things like our daughter and her boyfriend rent a little flat for £300 a month, and people just look at me like I am lying when I say it. £300? Really? (head tilt!)
I have also told a few people I met my fave actor several years ago, and spoke to him for 5 minutes. NO-ONE believes me. Not until I show a pic of me with him!
And yeah my DH does the 'not believing me' thing too! (Not often, but occasionally.) And if he loses something then finds it, somewhere he wasn't expecting to find it, he claims that I must have moved it. And once or twice there has been something with the car (like a new little scratch,) and of course he notices it when I have been out in the car, so it's obviously me that did it.
Never takes the blame for anything and never admits to being wrong. Grrrrr MEN! (Like I said, it doesn't happen often, but he does do this occasionally!)