I used to worry as well keeping my devices mint given that I don't use screen protectors, but with good trade in offers minor scratches, dings are completely fine and fall under normal wear and tear. Only need to worry about keeping devices mint if you are looking to sell privately. Now a days I just use the phone normally without worrying about their may be minor scratches as I use the device. If after 6 months it's still in great condition then I'll sell privately if not I'll use it as trade in especially for Samsung pre orders since their trade ins are pretty good.