And avoids using a mixer that decides to screw you over, and avoids using a mixer that gets taken down because hey - guess what? That's basically money laundering and the jail time for that sort of thing can be pretty hefty.
A mixer is not “money laundering”. As I understand it, “money laundering” is when you conceal from somebody, usually the tax authorities, the reason you have the money. If someone has no income to speak of, and still has a lot of cash, that’s suspicious. A “mixer” in this case would be analogous to exchanging the physical bills for bills with different serial numbers. But this does not alleviate suspicion, the problem of the money being unexplained remains. So they can “launder” the money; i.e. pretend that they have a hair salon business or something similar, and then declare that a lot of people are coming to their salon and spending money, even though there aren’t. But this now provides an explanation for the amount of money they have; the money is now “laundered”, even though it’s the same physical cash as before.
That's true. You never mix any more than you're willing to lose. And sure, it's money laundering. But money laundering in defense of freedom from oppression is OK, as I see it.
I'm OK with that. And it's impossible to avoid, if you're using systems with any chance of protecting your privacy. Also, criminals tend to attract lots of attention, and they're often careless, so they act as canaries.
There is the concern that you'll end up with Bitcoin that's been tainted in one way or another. However, at least some mixing services get coin from miners, so it's clean. And you can check for that in the blockchain.
That's mostly a concern when you're mixing Bitcoin before converting it to meatspace fiat. If you're anonymizing Bitcoin purchased with meatspace fiat, it doesn't matter so much if some is tainted. Or at least, it won't unless tainted coin gets blacklisted.
Admittedly (!) exaggerated, but are you not also providing cover for criminals by doing not essential things (like playing tennis), because criminals would be catched easily if no law abiding citizen would do that kind of things, right?
Most mixers use CoinJoin, which gives you trustless assurances that you won't lose your money. The worst thing you'll lose is your time.