Thinking about it, is there ANY fee that would make it worth it to give out bitcoins in exchange for potentially tainted coins that are possibly connected to crime and fraud?
The mixer admins you're discussing don't get arrested solely for handling "tainted" bitcoins. We all get those sometimes without facing legal consequences. Consider this: What if a criminal deposited money into Stake, and then you got them for your weekly payment? Highly plausible.
Mixers get shut down and their admins arrested because they frequently operate unlawfully. Yes, authorities aim to shut them down for assisting criminals in mixing their coins, but they typically target them for failing to comply with regulations as money transmission services.
Could mixers be honeypots? It's not an unlikely possibility that mixers are created and operated by state agencies as a way to catch high-profile criminals that are under the impression of "masking" their transactions.
Perhaps. However, let me pose a question to you. Considering recent events, do you believe criminals will continue to trust mixers? ChipMixer, SinBad, YoMix, and numerous others have been effectively targeted by authorities. If you were a criminal, would you risk trusting a potential trap instead of simply sending everything through the most secure and decentralized mixer available, Monero?
As someone working for the NSA and proposing to establish a honeypot, how would you address this question?