I think you miss the point, Sirius. It's a very real concern for vendors who have to regularly cash out hundreds or thousands of bitcoins. You don't come up with that kind of quantity from mining. And they can easily check and notice that there haven't been any sizable quantities won at the online gambling sites recently.... so where are the things coming from, and why is it a stream of BTC and not USD? Tax evasion. Money laundering. Conspiracy to commit fraud. Etc., etc., etc.. Buyers aren't the only ones who have to deal with BTC, after all. But yes, I agree... to worry about getting caught from spending less than 100 BTC every few weeks is probably pretty silly. They have more pressing matters, I would think.