Some people don't give a rat's behind about how they look while touring. I can't tell you how many times I overheard people say that a backpacker looked "dirty" or "like a bum" or "stinks" while travelling around the world. In Panama where I do some work, it's common to see travelers that look really filthy from days of being on the road where there are few facilities to shower. Plus it is really hot and humid which does not allow your clothes to dry properly, so you stink. When hiking here it takes but a couple of hours for you to both get really grungy and stink plus be sticky wet. Yikes!
Trying to look smart and/or presentable helps a lot with the locals. They just plain treat you better. Stupid little things like shaving, not having clothes with holes in them, etc. go a long way because in poor countries people are trying sooo hard not to look shabby. Once in eastern Europe I was backpacking with some less than perfect clothes and found no one would talk to me at cafes. So I went into a local store and bought a smart, lightweight coat of the kind often used in Europe. It was 100 bucks which I could hardly afford. But it looked right smart and hid most of my clothes down to my knees when zipped. Sort of like a really smart looking motorbike touring jacket a la BMW. Wow, what a difference. My social life really improved! Even got invited into some folks homes to get cleaned up and shower. It was a great investment. Never forgot that lesson. Ever since I invest a little tour money trying to look good-enough by local standards.
Another technique to "look clean" rather than "be hygienic" was to throw away faded clothes after 2 to 3 weeks and buy new ones wherever I was at. Always kept the weight low but a fresh supply of ok-looking clothes was at hand. And always kept one nice shirt in store for going out at night. Guess it was luxury touring of a sort, but I saw no reason for total deprivation on extended tours.
Also, about keeping the good-travel-ambassador look abroad: I tried not to have hanging clothes off my person or packs. Nothing wrong with that really, but in many places it's considered really low class. Of course YMMV and sometimes there's no choice since there are no places to dry out.
Guess keeping clean and looking smart are two separate, but related, subjects. One is good for the soul, but both are good for your social graces.