We recently outsourced one of our departments to become a company of its own. However they still get certain services from us - among others, all internet services including PPC management. In order to make billing easier, I created an MCC account and established the new company as a new account/client within the MCC. Then I started the tedious task of "moving" all campaigns from the old account to the new account. "Moving" means cutting and pasting all keywords, all ads, all copy etc. to the now account. I thought we had 2006 and Ajax nowadays....
Now guess what happened:
I previously spent some 2000 US$ per month for the campaigns in question.
After the transition, I only spend about 500 US$, plus click-through rate is higher plus conversion rate is higher.
All that has changed was the account who ran the ads. Everything else - keywords, CPC, ads - remained the same. My only explanation is that - very much like a Windows installation - the old account got polluted over time. Creating the new account was sort of a general reset.
Well, as usual, don't try this at home. But it worked for me.