i have hella stretch marks cuz i used to be fat with small muscles. then gained muscle, then lost fat, then gained more muscle. my biceps look like a battle field.
I got them really bad during puberty. they were all red and 3-dimensional, running from my biceps to my upper chest. I was fat and I grew fast. They just went away in time though. I got some on my biceps when I first started lifting. those went away too. now I have new ones. I guess I'm lucky, although I don't really care about them one way or the other.
i jsut noticed i have old stretch marks on my lats too, near my shoulder. that must just be from being fat, since they are old and i never used to workout my back when i first started lifting.