I have learned that I still haven't seen anyone cash out a relevant amount of signature earnings (let's say above $10000) at least in a place that's relevant to me, so I will remain skeptic and just hold it and see how I go about it in the future.
Im still worried about the mixed coins that I did mix to test a mixer out years ago (years ago 1 BTC was worth like $200) and so Im worried about cashing these out then not being able to explain where they came from and getting it counterfeited. Same goes for BTW that I withdrew from dead exchanges or lacking information of the trades in any way. Im not sure if I will ever be able to cash out any of these... so I may have to stick with signature earnings and other coins in which I can clearly trace the origin, otherwise it's extremely risky to cash them out because you don't know what the hell to expect.
Well, I've never sold any but I have spent plenty. Some of this was experimentally mixed just like you. Some of it was from sig campaign earnings from Bitmixer which may well be looked deeply down upon some day.
All of it, many thousands in total, went through Bitpay. They happily took it and I got plenty of tat in return for it. Go drip buy some gold or some race horses. No one is going to harm or kill you. Any vaguely clued up accountant will be able to join any dots that are questioned. There should be enough scraps out there to satisfy anyone.