I think the IRL version of this is buying cocaine, rubbing it over all yor cash, and then using it as your cash without actually using the cocaine. It'll def just be ignored, as it's on a high percentage of notes[1] for any transaction anyways [2]. Banks use ml scoring algorithms and im not sure mentioning cocaine in notes for a RTP/The Clearing House transaction would actually go unnoticed.

[1] https://en.wikipedia.org/wiki/Contaminated_currency

[2] https://cipherblade.com/blog/tainted-bitcoin-isnt-what-you-t...