You don't look for smart people by looking for people who don't do stupid things, because you won't find any. You look for smart people by finding people who do smart things because stupid people don't do smart people things.

I'm not saying Adams is not smart because he has done stupid things, I'm saying that Adams has probably thought of himself as very smart while not smart at all in field X because it is pretty clear he has done that in fields Y and Z (which is the first clue).

The second clue is about the fact that the "smart thing" he came up with is quite simplistic.