a good idea might be that the scars have to have meaning.
for example, the other day I nearly cut off part of my finger. it hurts, and im quite embarrassed that it happened, but the scar is there. since there was little reason for it, it might only have a miniscul effect, hardly noticable at all.
but say, I was bitten by a dog while trying to keep it from my sister, and have the bite scarred into my arm, that would give the scar meaning, since it was given in an act of courage or whatnot.
also it should be noted that a lot of people take pride in the accidental cuts and scars that they have, so maybe give a peculiarity in that regard?