How does Poo Clean Hair?

I used to have a book called "Why, What, Where", which provided explanations to everyday questions, like "How Does Soap Work?"  It was a book for children, and the answers were simplified.  I remember that it stated soap pulls dirt out while water pushed dirt out, and that soap is made of things that we might consider dirty, like fats and ash.  

Bubbles (or suds) in soap do not actually help clean.  Their purpose is to increase the surface area that the cleaning agent comes in contact with.  Bleach cleans well, but has no suds.  There is also an industry standard of dirt, appropriately dubbed "industrial dirt", with which detergents are tested for validity.  Here is where my knowledge of how soap/detergent/shampoo cleans.  I decided to do more research into the the chemistry behind soap:

Soap cleans by acting as an emulsifier. Basically, soap allows oil and water to mix so that oily grime can be removed during rinsing.

Swishing the soapy water around allows the soap or detergent to pull the grime away from clothes or dishes and into the larger pool of rinse water. Rinsing washes the detergent and soil away. Warm or hot water melts fats and oils so that it is easier for the soap or detergent to dissolve the soil and pull it away into the rinse water.

Shampoo works in a manner similar to that of soap and detergent, except that shampoo will not leave soap scum.  But what if I only want to remove the grime, and keep the oils?  Well, that's why I am washing my hair with baking soda rather than with shampoo.

I've read that, to keep hair shiny, I should wash my hair in cold water.  This makes sense as warm or hot water melts the natural oils in my hair.  These oils give my hair a gleam.  I would like to keep most of these oils and only be rid of the dirt.  Possibly, by regulating the temperature of the water I am using to wash my hair, I could change the greasiness of my hair.  During the initial days of my no-poo treatment, I could use hotter water to rinse my hair, and, as my scalp gets used to getting no poo, I could decrease the temperature of the water.

References:  

http://chemistry.about.com/od/cleanerchemistry/a/how-soap-cleans.htm

http://ezinearticles.com/?How-Does-Soap-Clean?&id=629717
http://www.ehow.com/how-does_4698309_shampoo-clean-hair.html