The denomination doesn't mean much. When the mixer pays out 5 BTC, it must source those 5 BTC from a transaction that gave at least 5 BTC to the mixer. In the example, that's all of the transactions, but if you wanted to pay out 15 BTC at once, you'd be limited to the first two.

A transaction has only one source, so that payout is obviously attributable to the source transaction. If the mixer gave you 5 BTC from Whore, you're holding Whore bitcoins. If the mixer gave you 5 BTC from Kingpin, you're holding Kingpin bitcoins.

The idea is that 100 people put in the 5 bitcoins, then each of those 100 get back 5 bitcoins to a different address... yes, you can track the bitcoins themselves, but you don't know which of the new wallets belonged to which of the old wallets... the 5 tainted bitcoins (from an illegal activity) might end up going to a totally different person who had nothing to do with the illegal activities.

In your example, the original owner of the whore coins would end up with the kingpin coins and vice versa.

It is described here: https://en.wikipedia.org/wiki/Cryptocurrency_tumbler

Yes, I understand this idea, and it is what I mean when I say that the rules of operation of the mixer invalidate the link -- in reality -- between the coins that you got from a mixer (post-mixing) and the coins that were given to the mixer (pre-mixing).

But the protocol doesn't reflect the reality of the mixer; the mixer is built on top of the protocol. Within the protocol, those coins are still linked, allowing perfect tracking of coins as they pass through the mixer.

You can argue in court that your kingpin coins aren't really kingpin coins, but you'll always be hamstrung by the evidence. What you really have are plainly-labeled kingpin coins and an admission to purposefully receiving contraband.