You have a point but it depends on the mixer you are using.The log policies vary accordingly, bitmixer.io has a strict no-logs policy.Taken from the Faq:
What logs are kept?
Absolutely no logs or personally identifying information are kept regarding your use of the Bitmixer service. All logs are permanently removed from both our website database and from our Bitcoin wallet after your coins have been transferred out of our reserve. All forwarding entries are removed after 24 hours.
How can you check it? Why do you believe to them? I think only because you're wear their signature and paid by it.
I can say that I'm Donald Trump or God Emperor of Humanity. Would you believe to me?
Self mixing would always leave the trails behind regardless of your rotations.
If you're have necessary skills, time and money you can write your own mixer with multi inputs and outputs.
you can always contact the mixer site/company and ask them about how do they handle the transactions, i mean do they keep logs and share with government and ask them, will they share your private information on producing court order ?
if all is good, then you can go ahead.
but if the transaction is big enough, then i would start a mixing site just for front, and do mixing myself.
Interesting. Please, ask me if I'm Donald Trump or not. Go ahead.