I really don't care. If he looks good in it, then he should wear it. I personally like it when guys wear Underarmor stuff or other athletic clothing. Hollister jeans also look good, but there are so many other brands that look nice too. Even Walmart brands can look good.
If I like him, it's not really going to be a big deal. The guy I like can't even match half of his clothing properly, but that doesn't stop me from finding him attractive.
As long as it looks good, I'm sure girls aren't too fussed about the brand (unless they'll be wearing it)
From my experience of hollister merchandise (it's very limited this side of the Atlantic) I've decided that it's actually pretty poor quality stuff. I wouldn't be surprised if it's different over there though.