DS8 lives in football kits, he looks like he fell out of JJB every single day. I couldn't care less because they're always easy to wash and rarely stain despite him spending 90% of his time on a bike or playing football.
DS13 couldn't give a shit what he wears, so is currently sporting my skinny jeans (which are like capri pants on him) and a t-shirt that I suspect was a pyjama top with the slogan "I went to Harvard Law and all I got was this t-shirt".
Life is too short to argue with DC about what they wear. The only time I pull rank is family events when I lay out everyone's outfits and they all silently dress smartly and spend 3 hours pretending to be civilised before resuming their sloppy style.
I never dressed them in slogan stuff when they were small, although MIL liked to buy t-shirts with "boys will be boys" on them (which always made me cringe a little because, you know, it's 2011 not 1911). I also never bought them massively expensive clothes after DS1 vomited on a cashmere Christian Dior jumper on a train to Euston. It was like a scene from the exorcist with DH shouting "but it's bleeding cashmere" as though that would make the small child stop barfing down it's front.