If you ever get to look at a spectrum analyzer display sometime, the upping and downing of these spikes will be a little disconcerting. In his photos, for example, just look at the biggest prominant peak, and see how its shape does not look the same from photo to photo, and these are "screens shots, or frozen in time captures, then consider all the little ones. I am just sayin you need to understand your test equipments capabilities and limitations and your source signals same as well.
Well put!