There's no need to go out in search of the most abrasive scrub on the market. In fact, the only thing your exfoliator absolutely needs to be is oil-free. Evans and Von Hep say that oil in general is a huge no-no for fake tans: Not only can it leave a residue on the surface of the skin that may interfere with the self-tanner's development, but it can also break down the solution and cause awkward fading. Instead, find a gentle scrub that will buff away dead skin and prime your body for an even glow.