Are we to understand that David Letterman is regarded (by whom ?) as something of a style icon ? The mere fact that we are discussing his habiliment on this site should seem to suggest that he is indeed so regarded - by some, anyway .
Here's something else which I fail to grasp : 'loafers' - if, by the term 'loafer', is intended a moccasin-style slip-on - have been happily mated here in Europe with lounge suits for as long as I'm able to remember ; why do North American men have such a problem with this concept ? I understand that : (1) they began life as sportive footwear and ; (2) some styles - for example, Bass Weejuns - are not, ahem, suitable or appropriate accompaniments to a lounge suit (being somewhat 'rugged', if not downright clumsy), but I see nothing wrong in pairing 'sleeker' styles (Berluti's 'Warhol' springs to mind) with suits . Let it not be forgotten that everything is in a constant state of flux : Edward VIII caused a veritable scandal by wearing brown reverse-calf oxfords with grey and navy-blue flannel numbers ; his father WROTE him a letter complaining that he had never seen anything so "unsmart" [sic.] as a short (i.e. tail-less) dinner jacket !
Now, suits and sneakers ? If we're talking hi-tech Nikes, or something similar, then the answer must be a resounding negative . If, on the other hand, we're looking at a pair of (say) Etro or Pantofola d'Oro HYBRIDS, I've seen many stylish, confident, Japanese and Italian men carry this off with some aplomb . I don't think that I would mate them with a Savile Row number, but a summer-weight, unlined Neapolitan suit...maybe .