1script - 3:24 pm on Sep 26, 2013 (gmt 0)
Every single piece of advice I ever got from the AdSense team in 10 years I've been a publisher has been detrimental to my business either through diminished earnings or through ad placement hurting traffic. You can safely discard everything AdSense team is telling you (except of course anything related to policy violations) - that department of Google seems to be largely staffed by recent college graduates that have no experience in running a site, let alone any kind of business. Their advice is usually at best naive - I have no reason to believe they care enough for it to be deliberate - it's usually just sheer ignorance. Despite being able to access mountains of actionable information, they don't seem to make any use of it when they "consult" you, even on things as basic as ad sizes.
I got a personal message from Adsense
As far as the effect of their suggested changes on the overall site traffic - they simply have to clue. This is in part because of internal policies - the oft mentioned and loudly celebrated firewall between the AdSense and the search team seems to be very real and actually very bad for publishers because it makes the AdSense team so bad at understanding the effect of their work on the site's standing in Google search. But on a more general level, every time I talk to any of AdSense ladies (they seem to be almost exclusively young women in mid 20s-30s) - I get a sense that they simply don't give a damn about your business.