FX is a great market, but not for the reasons people typically think. The problem lies in brokers for the mass market (the little guy). If you're at a billion dollar hedge fund, you have access to an entirely different class of brokers (and those markets are full of intrigue...)

I second your claim ("9 times out of 10") for CME. Human nature is to assign a complex answer ("they're reading the tape") to something very simple ("my model is shit").

That said, front running happens on CME, too. Again, it is the same construction: consumer sending orders through a nefarious broker.