I too sympathise with hiding under a thick layer of make up, having been doing so for the last 15 years. (I am 30 now).
I also have neavus of ota under my right eye, if I don't cover it, I look like I've been punched.
I think I cover it well, but it looks crap if I'm tired or hungover. Going on holiday or when it's hot, is particularly difficult- you start to sweat, the make up drips, it's just not nice. Last time I went on holiday, I just wiped it off, forgot I hadn't any make up on, went into a shop to buy something and the reaction of the girl behind the counter made me so upset. It cuts like a knife.
At least we are lucky enough to be able to use make up to cover our marks. As some aren't so lucky.