That's not really what he's asking.

He's asking if anyone else thinks Luffy gets stupider over the course of the series.

I say he goes up and down. Generally yes, but occasionally, he does things that are...uncharacteristically intelligent.


For example(mid series spoilers):



The entire encounter with Laboon. Somehow, he understood the situation, and developed this rather complicated psychological plot to start a fight with Laboon, then end it midfight, giving Laboon something else to live for. And then, even comes up with the whole idea of the mark so Laboon would start hurting himself. His execution makes it seem like his normal stupid self, but it's obvious he understood the outcome of what he was doing.

Things like that are on a thought level much higher than he normally displays. Makes a person wonder if he's smarter than he seems, or if Oda just wrote him a little out of character there.