The Audi TT was available in FWD and AWD versions when it first came out. Those that know how the Audi TT Haldex AWD system also knows that the car is essentially running in FWD mode full time until wheelspin is detected. Then there were a few high profile crashes in Europe because they were spinning off highways at very high speed. So one of the first things Audi did was add a very small spoiler to increase downforce at the rear of the car, even on FWD models.
But I agree, the spoilers that ricers use are useless and may cause more harm than good to the aerodynamics of the car. The only huge spoilers that work are those that are designed to provide the proper downforce IN CONJUNCTION to other aerodynamic tweaks in the body of the car. The Subaru STi and EVO have huge spoilers, but they do work and were measured in wind tunnels.