Caveat: I'm not an expert.

Yes you're right, each fraction of coin can be traced back to where it came from: a block with generated BTCs at some point in the past.  

Not true for dollars, the serial number only tells you where that particular piece of paper was minted - nothing about where the value really came from before it was spit out of your ATM.  

I've seen tons of blatantly false information in the media about this.. claiming that bitcoins are "less traceable than dollars".  As I understand it, they truth is that they are more traceable than dollars.