I have just watched a repeat of House (or more accurately, about 2 minutes of a repeat). At the end, it shows the cured doctor going back to Africa to do Good Deeds. He slings his backpack over the shoulder of his nice clean shirt, and he walks out to front the media.
There is no way on God's green earth that a backpack that has spent 5 years in Africa would look so shiny and new. At the very least, it should leave a smudge on a nice clean shirt. My favourite backpack was an Alice pack, which I finally threw out a few years ago.
It started life as a vibrant green, but after two weeks in the shrubbery, it was light brown (thanks to all the ingrained dirt, oil, food and grease) and it stayed that way for its entire life. I gave it a wash after every major exercise, but the dirt never came out. Ever. It also smelled - rancid food that had leaked, gun oil that had leaked, manky clothes that had lived in it and sweat that had leaked out of me and other unidentifiable smells. The only place it could live "back in civilisation" was in the garage. It was not a pack that was allowed in the house.
Why was it so filthy?
It was the only chair I had when in the scrub. I spent hours sitting on it. Or sitting on the ground and leaning up against it as a backrest.
At night, it was my pillow.
I used it as a table to eat off.
I'd wash my socks in the field and then hang them off the pack to dry.
In short, it was a nasty thing. Indispensable, but nasty nonetheless.
Which makes me wonder why you could supposedly live in Africa for years and have a backpack smelling of roses.