Panthro - 4:43 am on Aug 17, 2013 (gmt 0)
Yep, big discrepancy even among G's own tools. I did a PPC campaign for a friend this weekend and even on ultra-low traffic there was terrible data. GA reports one thing, GWT another, and Adwords yet another. Not only number of visits but keywords, etc. Multiply that a few thousand times and I can see how some of you see some serious problems.
I think more and more you cannot rely 100% on GOOG's data for accuracy.