The engineering approach to alternative hair and skin care

Alternative hair and skin is a big business.  People sell books and sell stuff.  Some use scare tactics saying that some common ingredients are very bad.  Some just appeal to those organic people that what you don't eat shouldn't put on your skin and hair.

Those are long stories.  The problem is, you find the same home made receipts all over.  I bet most promoters didn't try it themselves, not to say if they ever rely on the alternative stuff long term.  I bet even authors will use the most expensive shampoo and conditioner when they have to appear in public.  Those with good results are hardly applicable to many other people.

By engineering approach I mean looking into cost, and time.  Tell a man to do an oil treatment every few days!  Also, what's the long term effect?  What can go wrong?

Some receipts are hardly practical.  A few dollar a bottle of shampoo and it lasts for months.  No hassle.  If you are afraid, try to buy expensive ones with mostly good ingredients.  So I almost gave up.  But I am interested in answering the question - are the skin and hair care company selling you a big lie?  That you hardly need any shampoo, or at least much cheaper.