(Bear in mind that these machines have drawn criticism for the somewhat explicit images they produce.)
Bear further in mind that my hair looks something like this in heat and humidity, although it is quite short.
In both directions of travel, after I passed through the scanner, a TSA agent physically patted down the back of my head.
Do you really mean to tell me that this crazily-, invasively-detailed scanner can't determine if there is anything hidden in my hair??? I call BS, big-time. But then, the alternative would be that those TSA agents were trying to make sure I looked good in any selfies I planned to take at the airport!