Since I published my article on ZWC [1] I've been scanning different parts of the net for their use after hearing about their use in Eve Online.
I've found them being used for quite some time, even here on HN. I think spammers are using them to get around spam filters because the context that they're using them for doesn't usually seem like they've been inadvertently fingerprinted. It seems like they're sending the same message over and over again on things like hiring threads for HN. I wish I had more time to dig into it, but there are too many more important things going on right now.
https://secretsigner.com