To almost every extent humans are advertisements from the shoes you wear to the cologn you spray on. If you smell good and someone says "you smell good what do you have on?" You answer "Polo" if the person thinks that it does indeed smell that good he or she may go out and buy it. The shirts you wear may show their name on the front or the shirts design may even be around the companies logo. Also there has been instances where people sold parts of there body mostly their head to advertise certain things. I dont now how they got into this but, it is true. People are walking talking billboards. The most effective and fastest advertisement is "Word of Mouth." Humans would rather hear from their friends or even other people on the street than listen to a lame commercial try and sell you an item. If you heard from your friend that the item was awesome or was better than expected, it would help sell the item more than the commercial saying "this item is saweet!"
Clothes, jewelry, shoes, etc not only advertise other brands, they label you. If you are wearing a new par of Timberlands and your pants are baggy you may have a collared shirt, a watch and ring people may classify you as a so called "hoodlem." Who cares what people wear what if they wear the clothes that are comfortable to them, just because someone doesn't dress like you or like your image of what they should wear doesn't make them any less of a person.