Buying clothing with prominent logos is the equivalent of working for someone else and then paying them for the privilege of doing so. Unless you are working to end world hunger (in which case a certain amount of charity is appropriate) this is not a wise strategy. You're not a walking billboard, stop treating your body like one.
Designers take advantage of gullible consumers willing to pay top dollar for a T-shirt cheaply made in a third world sweatshop simply because it sports their logo. You're not paying extra for quality, and you certainly aren't paying extra for style, you're paying more to brand yourself as a sheep. So do yourself a favor and pass on logo emblazoned clothing, it's baaaaaahhhhhd.