Just use a mixer mixer and a mixer 3-4 times. Problem solved. You could also deposit and withdraw from a gambling site.
How can you be sure the mixing service isn't a honey pot? And how do you know the gambling site (or a clever 3rd party) isn't fingerprinting every transaction?
I've seen a lot of suggestions for using very weak 3rd party solutions ITT but not a single trustless solution. I believe someone here (CIYAM?) is working on cross-chain atomic transactions that would effectively "scrub" links to past transactions, but that's in development (AFAIK).
mixers are very probably safe. If you want to be safer, use two 3rd party websites then two different mixers.
It depends, there are some mixers which turned out to be a scam. The coin will be under the mixer's owner control for a amount of time if the owner decides to run away, you may just lose your coins. If it is operated by FBI, you are screwed.
i think the most trust mixer just bitmixer.
But what is he function to hide your bitcoin ?
I think you meant what is the use. Bitcoin is designed to be pseudo-anonymous, not completely anonymous. Therefore, you can still get linked to your real life identity or other identity online. To prevent people from tracing the address, mixing is used to boost the anonymity.