I've got replace thingie suggestions and layout suggestions and add more ads suggestions. Sometimes I ignore and sometimes I test, but always I listen and consider it. Google has access to a lot more statistical information than I do or ever will. At one point they suggested I'd get something like a 60% revenue boost if I made a layout change and ran a different size ad - I tried it, and got more than a 100% boost in revenue - that's lasted over a year now. So yea, they got that one wrong, but I'll take that kind of wrong every day.
I think if you treat them professionally (i.e. politely) instead of complaining or blaming, you will get more and better help from them.
Heh, I used to email back and forth with one of our previous ASAs here, and she told me that outright. They don't mind criticism and they understand the frustration, but they're much more willing to put themselves out for people who are civil and professional.