I have no problem with this at all. Even Alaqua Animal Refuge benefits from the proceeds of a Mardi Gras dog parade. http://www.sandestin.com/portals/0/includes/pdfs/2012MardiPawsReg.pdf
IMO, even if the costume is ridiculous, I don't think the dog suffers in any way as long as he's comfortable and isn'tisn't struggling. I suppose you could always give the costume a tight fit and say that it's a designer thundershirt.