I only shower once every few days, sometimes as little as once a week depending how oily/sticky I'm feeling (I lead a pretty sedentary lifestyle so I don't reach that stage daily). People around me find it disturbing/disgusting but I usually shrug it off, telling them that it's unnecessary and that they're just wasting water showering once/twice a day.
I also see articles like this around the web skeptical of daily showering (though it's really only talking about skin health): http://www.cbsnews.com/news/is-showering-bad-for-your-health/
I also understand that people living in very clean environments during their childhood are more prone to certain health problems like allergies and asthma.
I understand that people who work in dirty environments (e.g. car mechanics?) will have to do it frequently but what about people who don't? Should we only be showering after we fall into a pool of mud or after a heavy workout?