Not to mention that Bitcoins are indistinguishable from themselves. So that'd be a very niche idea.
I've been a Bitcoin proponent for a long time, but this lack of basic fungibility is one of its major downsides in my opinion.
I'd say it's rather tainting transactions that use outputs of your "tainted" transaction. Personally I don't like bringing "coins" into discussion because people think it's something more material than it really is while in fact "coins" are just numbers in transaction outputs.
If you have transaction that sends 2 BTC to an address you can't taint 1 BTC out of it because in this scenario they are just numbers, like you can't distinguish both 1s in 1 + 1 = 2.
That you can track transactions back to their mining block is another matter.