Have you seen this research from 2013? Here is the original paper — http://www.pnas.org/content/110/15/5802.full.pdf ; but there is also different coverage from Wired and other sources.
It showed that having certain interests online would actually statistically signify a lower or higher intelligence. A signal of having higher intelligence was actually determined to be ‘The Colbert Report” and “Science”. Lower intelligence factors included “Lady Antebellum” and “Harley Davidson”.
I understand your argument and it makes sense. However, your headline of “The Other Side is Not Dumb” is misleading — statistically you can determine if a certain subset of population has a lower than average IQ. By some definitions, that is the definition of ‘dumb’.