No simplified tax code proposal I've read would eliminate the problem of people doing cash transactions under the table, or "loaning" themselves a house and treating that as a business asset.
http://www.fairtax.org/site/PageServer?pagename=HowFairTaxWo...
It's a tax on buying. Think about that for a moment. Fair Tax proponents claim that the current tax system causes disincentives for things like exports and U.S. manufacturing. Why would the Fair Tax proposal then not cause a disincentive on the demand side of the economy? ("How will the plan affect economic growth" in the FAQ clearly espouses a particular economic ideology that has yet to be supported by any of the facts of history.)
It also places the entire tax burden on the consumer. Annual pre-tax corporate profits are somewhere between $800 billion and $2 trillion, depending on which data you decide to believe. Why is all that money being left on the table in favor of drawing the entire national budget from consumers?
Corporations are owned by people (consumers as you call them), tax the person, not the intermediary.
And in any case the corporation would also have to pay the tax on everything they buy.
This might help your customers, but it doesn't help you (unless you charge the sales tax and don't forward it). So the cheating incentives are much lower.
"With the prebate program in effect, those earning less than $15,000 per year would see their share of the federal tax burden drop from -0.7 percent to -6.3 percent. Of course, if the poorest Americans are paying less under the FairTax plan, then someone else pays more. As it turns out, according to the Treasury Department, “someone else” is everybody earning between $15,000 and $200,000 per year. The chart below compares the share of the federal tax burden for different income groups under the current system and under the FairTax. Those in the highest and the lowest brackets will see their share decrease, while everyone else will see their share of taxes increase."