I do the same as you, washed and folded. Check for stains (don’t forget the underarms), missing buttons, holes etc. If anything’s wrong with it I bin it. I know I could attempt to repair things but I also know it would sit in a pile forever waiting for me to do it. There’s no shortage of clothes in the op shops so some things just need to go in the bin. (None of my clothes are designer or valuable in any way). I don’t buy much from op shops, but if I do I always wash before using.