If I am on the way home from a ride, I won't let my bike attire stop me from completing errands. If the store is too yuppie, I might put on gym shorts over the bike shorts. Anyway, I think it wise to let them know you are biking. The Smell. Gives them cause to understand my overall condition.
Besides, where I am living now. No one thinks a thing of it anyway... Cyclists are everywhere.
But, does anyone wear cycling clothes, if not out on the bike. Cycling clothes feel great on the bike. But, after about 5 hours, seem a bit binding to one's parts; if not on the bike.