I am certainly no Huckabee supporter, but it is very clear that you don't understand the FairTax at all.
The FairTax isn't Huckabee's idea, it has been around for quite a while - Huckabee just adopted it and it is pretty much his only good idea.
I admit that I am fairly clueless about economics. Buuuut: I was joking. However, two flaws with the FairTax are that it is only an improvement if the IRS goes away, and it's difficult to imagine folks in DC giving it up, and that underground economies will always exist, in some way or another (there will always be bad guys).