What is chain analysis?
It is when individuals or companies take advantage of the fact that blockchain is fully transparent, trying to figure out and subjectively interpret what is occurring inside it.
I searched multiple engines and two common results are companies selling a service.
Yeah, some companies make money selling their subjective interpretation of what's happening to other companies, exchanges, law enforcement agencies, governments, dictators, and also surveillance-oriented wallets like Wasabi Wallet.
One of the companies claims to be building trust in blockchains lolz. The blockchain is already trusted that's the point.
This one is a ridiculous claim that they employ to siphon money off from people who naively believe surveillance companies provide valuable services and actually know what's going on.
By what method to these companies determine which coins are tainted?
The point is they do not "determine", they gave themselves the power to unilaterally decide which coins are to be deemed clean and which aren't.
Are their methods audited for accuracy?
How would you audit subjective interpretations?
Does Wasabi Wallet do their own chain analysis?
Of course, they do, how else can they determine that some inputs came from Wasabi 1.0 or that particular UTXO has a particular anonymity set if not by looking at analyzing blockchain data?