Dressing to be respectful, situation appropriate and comfortable is smart for all travelers. But, I always find this topic amusing.
When my daughter was in high school we lived very close to Walt Disney World. One of the things she and her friends got a kick out of doing was to go "tourist spotting". This involved going to one of the locations frequented more by visitors than locals to simply watch tourists and try to figure out where they were from. The girls were pretty accurate and learned how to tell if they were British, German, South American (Brazilian, etc.), midwestern US, among others. They said the secret was the way each group combined clothes to try to look "Floridian". After making their guess among themselves they would start a conversation with the "subject" to determine where their home was. So, perhaps wherever we come from, it is human nature to want to "fit in" wherever we are visiting. But, unless we are truly local, we don't understand the slight nuances of shorts length, skirt style, color combinations, cut of pants, hair styles, etc. that are peculiar to a region. With the rise of international clothing chains selling the same thing everywhere this is becoming less and less evident but many tourists are still easy to "spot".
As a side note: while doing this the girls would sometimes befriend a family or small group and have sort of reverse "Rick Steves" experiences, becoming unofficial tour guides or having them over to our home for dinner and a pool party. Over the years we have kept in touch with a few of these overseas friends and have visited them in their own countries. So, being tagged as a "tourist" can be a positive thing!