Things that virtually nobody notices or seems to care very much about when it comes to clothing make, colour, style, etc… but irritate you (when nothing more pressing is on your mind).
Men’s dress shirt single breast pocket. Who besides Dilbert carries things in that pocket anymore?
Men’s dress shirt placket. I prefer a clean (french) line down the front of my shirt. A traditional placket is often stiff and buckles and breaks that simple elegant look, especially since wearing a tie is becoming less and less necessary for men’s business attire.
Shirt buttons that yellow and crumble. You’d think by now clothes manufacturers would come up with a material that dry cleaners could not destroy in a matter of a dozen or so cleaning cycles.