All fake tans contain dihydroxyacetone, which is a chemical that reacts with the air and gives the brown colour on your skin. Unfortunately, it does have a smell of 'biscuits' or 'vinegar.' The manufacturers of the creams add perfume to attempt to counteract the smell but unless there's a fake tan that I've missed, none are 100% successful. Even if the cream smells lovely in the bottle, once it is in contact with your skin and the air, the 'fake tan' smell tends be predominant.
St Tropez is a good fake tan but it still has that smell, although it is one of the milder pongers!