Yep. A national sales tax nail those who hide income --- assuming they consume.
I believe an income tax should have been unconstitutional. However, a national sales tax will be open to abuses similar to the income tax. Many more items will be sold on the black market.
My wife, for instance, is a bargain shopper. She's as likely to buy something at a yard sale as at a store. Unless the taxes are charged at the manufacturing site or at the ports the goods come in on, a national sales tax will solve nothing.