One of the most useful uses of the Hair Part Theory is to both create commercials and/or explain their effectivness. The latest one is the charming Dad explaining about how is daughter will not wear anything other than her Princess Dress, even though it will get stained and dirty. http://great-ads.blogspot.com/
2013/01/tide-and-dad-star-in-princess-dress.html
It’s a classic “new man” commercial, where the Dad is the one being the caretaker, nurturer and laundry do-er. So in the 30 seconds it takes to establish both the premise and message, they use a handsome right hair parting man to show an empathetic, kind, understanding (and domesticated) man. The right part makes it easy for the judgement to be quickly made by the viewer that it makes sense.
Now, look how he looks flipped, with a left hair part…not so sensitive, wouldn’t you say? 
About John Walter
A long long time ago when I was just 19, I discovered the effects of changing my hair part from right to left. The strength of the change - in my case from a social misfit to "Joe Popular" was amazing, and not only that, when I looked around, it was happening to others.
The Hair Part Theory was the result of researching the effects and putting it into a more scientific framework and language. My sister Catherine Walter was instrumental in getting my vague handwaving theories into a great paper, including a slew of statistics to illustrate just how many leaders we have that are hair parters!
A few years after discovering the Hair Part Theory, I discovered, or more accurately re-discovered a true image mirror - and recognized myself at a deep level. The full story is elsewhere on this blog (link coming), but suffice to say that the True Mirror (the trade name of my perfect version), reflects your hair part the way it actually is, and you can see exactly what you are projecting...it matters!
Hair Part Theory - Discover the Difference! 