When I started teaching at a Midwestern university, secretaries would mistake me for a student,
so I wore a coat and tie to class so the students wouldn't mistake me for another student. Two or three students immediately told me in written course evaluations
, "lose the tie". So now I wear a herringbone or glen plaid coat, no tie. Recently decided to upgrade my image, but I know I'll get teased by faculty colleagues at first (administrators wear coat/tie or suit, but few faculty wear even business casual, even in class). So I figure it'll be good shoes first, then I'll sneak in a pocket square every now and then until it becomes standard. It'll happen, I'll just be sneaky
(I doubt I'll ever go back to the tie, though. Students seem intimidated by it).