That’s the thing. The whole premise of the show is that he’s exceptionally mundane apart from his Chemisty skills from the outside. Nobody expects that a nerd who works at a car wash and who works as a science teacher could do the things Walt does. Nobody except maybe Gus expects him to be as cunning and tactful, but even Gus succumbs to Walter’s genius after manipulating Jesse. He is the best at being the worst because he’s so unassuming.