I am assuming when MEW got hacked, or when companies mass produce thousands of wallets for their private keys, that some person trying to diminish their tracks by routing their ill gotten funds thru these wallets could end up getting an unknowing users wallet / address also blacklisted.
Then again, maybe i'm just paranoid and over thinking things due to my espresso drinks this morning.
Bitcoin is property. Property is subject to law. Exchanges can't just help themselves to your property. Things may be a little woolly at present but you're not wide open to whatever whims occur to them. There's a process that needs going through.
That's conditional on using an exchange that has identifiable ownership of course.
But this is my point and the problem: Bitcoin is property only in certain jurisdictions, in others it's considered other things, so other laws apply. Then there's the different ways in which certain jurisdictions deal with property.
So what we have here is that you deposit Bitcoin an exchange, and then depending on were you and the exchange are sitting, different things will happen. Which means, you must understand the ongoing laws, and you must look up for past situations to compare with what you are trying to do.
As of right now, depositing coins which you don't know the history origin from in a Bitlicense-friendly exchange, or in general any of the major US-esque exchanges at least, is risky. Im sure they have internal blacklist servers for certain coins from some histories i've heard.
We need laws that will protect us from this bullshit, then we need to support exchanges that are hosted within jurisdictions those laws apply.