Let me give you an example: at BitcoinMixers.com you can find Helix light mixer that does not just clean your bitcoins it gives you brand new freshly mined uncirculated bitcoins. The Helix's system is more than a simple bitcoin tumbler, it is privacy and security wrapped in one. 
Where did you get newly minted coins?
our website is only concerned with advertising these services. where the team of BTC mixer takes new Bitcoins we do not know. maybe this is the secret of the company
Or is it possible maybe it's not happening? If you cannot explain or show it happening.... i don't know if it should be advertised.