Some traders may not buy from you if brand. If you care about following your calves, maybe you don't want to sell to those traders, anyway. But some that will tell you where they went still aren't going to want them branded. There will be some exhibitors that won't want them either, probably especially those who show slick shear.
We're feeding a steer with a brand this time (a big, ugly and not well known brand), but he was a really good buy, and I believe that was partly why. Given a choice, I'd much prefer he didn't have it, but I guess it's obviously not an absolute deal breaker for me.
Ear notches are a lot like brands, not very attractive (especially multiple ones) and could be a deal breaker for some. Tattoo's aren't going to hurt their value/price, but I'm not sure they're going to do much good, because most folks (especially if the trader is still helping them) aren't just going to let you look in their calf's ear to see if you might've raised him... Guess a few might, though.