I started to comment on this yesterday, and then decided to keep my big mouth shut. I'll probably wish I'd stuck with that decision, but the old editorial reflexes won't be denied.
I have some very strong opinions about free advertising, a holdover from my days in the newspaper business. There's a very fine line between recommending a favorite singer or group and being a shill for a commercial organization, and it's sometimes really tough to know where that line is. My rule of thumb is, if they're able to pay for the advertising, don't give it to them free.
Same reasoning applies to T-shirts. I will have no problem at all wearing a Mudcat shirt (make it an XL, Dick), but don't try to sell me one advertising your favorite beverage.
There. The grumpy old man has vented his spleen. Susan, pick a tune. I'll sing tenor.