that Walt is a loser in what “counts” in life. He has to work a second job at a car wash to supplement his crappy high school teacher income. His wife loves him but does not have much respect for him. His son is handicapped. For heaven’s sakes, he drives one of the worst cars ever made.
The irony is that while Hank is a successful DEA, he’s overconfident and obnoxious. He doesn’t suspect WW solely on the basis of being a bit of a straight-laced nerd but moreso because he completely underestimates WW as a human being based on his position in life. To him and everyone else in his life, WW is a big nobody.