Interesting research coming out of Uni of Cambridge. Can bitcoins be tracked? ... used to have issues with tainting the bitcoins but current technology has lead to practical ways to trace stolen bitcoins. im not sure what this means for you and me, like what happens if somehow stolen bitcoins land in my hands... but interesting nonetheless.
Video: Stolen Bitcoin Tracing - Computerphile; practical way to trace stolen bitcoins It's nothing new, Chain Analysis has existed for quite a while now. You have to be careful with whom you deal with. Scammers most likely will move on to using anonymous Altcoins.