Bitcoin dont move! they just change adress after trade!
So what is the point of taint tracing all coins are tainted within no time!!!!!!
there will be no new bitcoins when tainted , its like dollars with coke traces!
even worse , bitcoins cant be replaced!
The more users the more tainted , and dont forget 1 bitcoin can be hold by 100.000.000 address at the same time!
So clean coins is a illusion!

If someone gets some tainted coins they can just start sending satoshis to all the people they don't like to taint their addresses.