Hi Emily,  For several years I've been washing my hair only ever other or every three days.  I've found that my hair gets less oily.  Just think of the savings in fuel for the nation--no more trucks crisscrossing the country full of shampoo--and the supermarkets could decrease in size by a tenth.  Now if we could all switch to just one brand of dog or cat food...!  I can see the headlines:  "Economic Dowturn Blamed on Austurity."  "Obama Says Different Foods For Different Dogs."  "Clothing Detergent Sales Green As Pillowcases Brown."

Hi Emily, thanks for the info. Never heard about this new trend but I think it is worth a try! Sure, hygienically it's a bit repulsive, but there are ways to minimize the danger- have them put up together in a chignon (the oiliness will show less too), maybe wearing hats as well when going out (my fear is actually to get lice in the metro from some kid sitting nearby- unwashed hair is an open house invitation for these little animals). I will try it sometime on a vacation, when I'm up in the mountain in a little cabin, and will comeback to report:-)
It will be hard though, just reading this tread makes my head itchy and I will certainly break after a week.

I didn't know it was a trend either, but I can see why.
I found out by accident when I was in my teens that my hair looked fantastic after not being washed for a few weeks in summer.  At the time (in the 60s/70s) I didn't think I could get away with shampooing less than every three days, but I did know that my hair was happier not being washed.
In my thirties I found J.R.Liggett's bar shampoo, and that seems to strip less of the qi out of my hair, so I've been using that since, when I do shampoo which is some times after some particularly sweaty or dirty work.
I can't think of many public places where I would put my head down, and I do tend to wear hats a lot outside of the house, but most dirt will come off with a warm rinse, and when it's smell from some place that I've picked up, even a packaged herbal tea will make a nice quick rinse, although I tend to want to make my own.
Back in the days when I used to shampoo every three days, my hair got greasy by the middle of the second day, dry and needing to be conditioned after every wash, electric in any favourable weather condition - my hair was almost always hell, and timing a window when it might look good took major planning.  Now my hair no longer seems thin and lank, and I get compliments often, although some of that may be because at 54, I still don't have any white or grey hair - a genetic thing nothing to do with shampoo issues.