Senator DeMint, a Republican of South Carolina, had an op-ed piece in the Washington Post over the weekend arguing against legislation to impose a $10-a-tourist tax on foreign visitors to America that would be used to create an industry-controlled tourism marketing campaign. He writes: "Imagine: 'Come to America, so we can tax you at the airport!'"
There's nothing stopping hotels or theme park owners from charging higher prices and using the money to fund increased marketing. That would be a private decision. But if Washington does it, the politicians can then go extract campaign contributions from the hotel and theme park owners. The foreign tourists who would pay the tax don't vote; this would be taxation without representation.