Hi Tracy,
The GMAT is a standardized test. And like all standardized tests, it tests how well you take this particular standardized test. You "take" it better when you 1) know the tested content, 2) know the format, 3) use effective strategies for each Q-type, and 4) are comfortable with the pacing/timing guidelines.
So, I don't think ANYONE is "too stupid" to take the GMAT.
That said, there is a LOT more to GMAT study than the OG, although the OG is pretty much everyone's starting place.
I think you'll get more helpful feedback from the BTG forums if you can go over in depth the materials you've used, when your test date is, and where more specifically your problem areas lie.
