One of the painters at the art school asked to use me as a subject for his next work, so I said sure. He was very amenable; he did some sketches of me while in the office so I could get my work done while modeling. And while he was setting up, I kept thinking about how the result might end up looking.
Initially, I was a little uncomfortable. I was thinking about how my skin was broken out, how my beard was scraggly (no matter how much I try to tame it), and how when I'm not explicitly smiling, I look like I'm angry.
There is an idealized version of myself that I like to imagine. I don't look like Brad Pitt, but I look nicer than I do. I would love pictures that people make of me to be idealized, to ignore the blemishes, and make full, well-kempt facial hair. But artists don't do that unless you're paying them for it.
Artists seek humanity. They want to capture what is unique about their subject, to show what is compelling, and that means accentuating (or at least acknowledging) all those things you hate.
All of us have things we don't like about ourselves. Some of them are physical traits, others are the thoughts or tics we have. We see them as flaws, things we are ashamed of and desperately try to hide. Any time you see a picture or a video of yourself, you lock onto those flaws and you are disgusted by them. (Ever notice how a picture of you and your friends, you never think twice about how your friends look, but you always think you look ugly or stupid?)
The reality, though, is that they aren't flaws in everybody's eyes. For some people, your "flaws" are your most interesting or distinguishing characteristics. They are what make you a human being and not another boring clone.
If you write about a real person, or base a character on a real person, know what you're getting into. You may have the best of intentions, and some people will be honored or humbled, but sometimes people are disgusted at what they see on the pages. Whether you exaggerate their distinguishing traits or you express them accurately, it's bound to happen. If you can handle the situation when it comes up, explain that there is no offense intended and that you were sharing their compelling and intriguing attributes, then go for it with due confidence. If you'd rather not have to deal with that mess, then make sure nobody can ever figure out where the inspiration for your writing comes from.