is usually not the main concern.
I think a related and more important concern is to dress in a
respectful manner when we are guests in developing countries, esp
when in people's homes or religious sights. The usual
"uniform" for most of us that I remember looked similar
to what we call pyjamas back home. It tends to look sloppy to
locals at times -- and therefore they may take it as presumptious
or rude if you are invited to their home for sunday dinner,
birthday parties, etc.
"going out to night clubs and dinner" is not the same
type of experience when you are in developing countries. There are
not "formal" events on the road. There are, however,
times to be a bit more understated and respectful.
The main point: let it all hang out, when you are in the midst of
a throng of tacky tourists. And then tone it down and wear neat,
clean clothes, perhaps a pair of light pants (not jeans), plain
shirt, real shoes, when you are a special guest, etc. ALSO, dress
a bit more conservative when crossing boarders. No need to invite
guards to harass you.
You say you are headed to N America and Europe too.. the above
doesnt apply so much to some of the more culturally dominate
countries. But here, depending on what kind of social life you
enjoy, you may want nicer clothes. Still, though, a clean pair of
"dockers" type pants in good repair, and a conservative
shirt that you pamper and dont stain too bad, is all you will
need. Real shoes can help too. Clean clothes that are not ripped
up, and if you dont smell bad and have good manners...that will
get you pretty far.
talk less, listen more.