Just read this. I guess I agree that the government agency doing this stuff will probably get it all horribly wrong, and it's very abusable. But I was thinking, something similar could be right and good:
What if police see something suspicious, and just ask the guy what's up? I think our laws say you don't have to incriminate yourself or answer, and if you refuse, the police can't do anything. But a good person will recognise that what s/he did *was* a bit suspicious, and, taking into account privacy concerns, will want to tell the police some info to let them rest easy knowing s/he didn't do anything wrong. A good person will not say "I refuse to answer." At worst, a good person will think a bit and say "I really can't think of anything I can safely tell you b/c of privacy concerns, sorry." So, like, the general idea of trying to go after people who have all this nice shit and won't tell us where it came from and otherwise act like bad people, does make some sense.