They imagine that others will be turned off by the sight of something ugly. And this is largely driven by media conditioning that teaches so many westerners to overvalue personal beauty.
If it's emotional scars, the fear can run even deeper -- fear of being rejected once it's discovered that someone has PTSD or is a survivor or childhood abuse or other misfortunes.
I agree. I think that minor “imperfections” (for lack of a better word) are negligible. It’s the same with breast’s that are not symmetrical one to the other, one leg a little shorter than the other, etc. In fact, one feature I find oddly attractive in some women is when their mouths or teeth are slightly flawed in some way.