If what I've been told by people that used to work on those very Google Adwords teams, it's not that they are "bad" at their job, it's that they are meant to meet a certain quota of spend and nothing like ROI etc matters. What's the solution to campaign doing badly? Up the budget! They know it's not optimal, their managers know it's not optimal, but the goal is for Google's bottom line. This stops once you reach a certain spend tier and they know the burn out rates for those companies improve and they want the longer term revenues. (This is also good for larger agencies, since they will also get the good treatment from being a premier partner.) The lower tier spends are basically "boiler rooms" peddling fake penny stocks. People trust them because "It's Google!" but that is so so far from the truth. Sometimes it's not even Google, it's a company they've outsourced to, and sometimes they even work in the same building as Google.