This seems impossible to enforce for the consumer. If I buy $700 worth of stuff on Overstock in BTC that I paid $500 for how is the IRS going to track this or even know? Am I just on the honor system to report it? Good luck with that...
Yes.
Income taxes are "voluntary", Harry Reid said so.
They're voluntary, but your basically risking an audit everytime. Even if it's a small risk, I wouldn't risk it personally.