[not too stupid]

How so? If someone paid a painter $600 in cash under the table to paint his house, how would the FairTax catch this?

The fair tax taxes consumption not income. Any serive you buy is not taxed.

[Somewhat Centrist]

Um, dude, that would exempt some 70% of the economy. The tax rate on goods would have to be astronomical to make up for that, like 300%, and then people would spend even less on services...

There is no way that would work, even if people continued to buy goods at the same rate the underground economy for goods would take off bigtime.