One of my good friends had a lot of stretch marks on his body(his chest and stomach, and even some wrapping around to his back) prior to top surgery, and he still has them in some places, albeit faded. They were red and irritated looking when he first had the surgery done, but it's been a couple years and they're paler and not very noticeable unless you're outright looking for them. Some of the bigger ones look like dark scars from an accident or something, but again, they're pale and not immediately identifiable as stretch marks unless your goal is to label them as such.