Italy is the place I've felt most inclined to want to present my best appearance.
--For a quick cover up, dark rain pants over bike short work well.
--Even in the U.S., I always make a point of taking off my bike sunglasses before entering any business. That seems like simple politeness to me.
We didn't enounter any friction in Italy last year when we would stop for coffee and pastires or lunch while out for day rides. Maybe thats was due to the fact that where we were (northeast), so many people cycle. Cyclists relaxing in cafes was a common site. (One Sunday we saw easily hundreds of other cyclists doing group rides during a 30 mile ride of our own.) But for generally going about town after the riding was done, I definitely avoided the shorts and t-shirt look.
When I toured in Andalucia over a decade ago it was during a time when you did not see native adults wearing shorts. It may still be that way today. If I stopped for a sit down lunch, I put on my black rain pants and a light sweater out of respect for the local custom.
The removing the sublasses thing is another very good point.