Careful. You think Danky polices the trivial now, just wait until he’s into his second Mike’s Hard Lemonade and feeling mean. That boy can sniff out a typo like a truffle hog.
I’d argue that such is always expected. Grandparents always buy some clothes, and kids (including teens) never really appreciate them over the other, flashier gifts. It was just an expected part of the holiday for me growing up. It didn’t mean my grandparents didn’t know what I liked or enjoyed, or they wouldn’t have also gotten me the things I wanted.
Sure, if those were the only gifts they got, I could see the issue. But the OP makes it sound like it’s one or two of a bunch of gifts. And that’s just expected. You get clothes that you don’t like wearing? You can wear them around the house or when you visit or are visiting grandma. That’s what I always did.
Plus, with clothes, there’s always the risk that they won’t fit, so you have a built-in reason to use a receipt. So, if you really must take it back, you can do so yourself.