To be fair, Americans are pretty extreme in their hygiene habits, just as they are with everything else. My sister spent a year in France and discovered (to her horror) that it's true: French people shower once a week, and to them that's perfectly fine. It's whatever you're used to.
I'd bet that most Americans don't actually need to shower every single day. If you use deodorant, or heck, just apply some perfume or cologne every day, you'll smell fine unless you've got some kind of horrible disease that makes you detectable from across the room. Seriously, what the hell are you doing that makes you smell so bad?