Religion: Muslim 10-15%
Income: $18466 USD
edit: from browsing more random "agents", there are a lot of 5 y/o's making tens of thousands of $ per year:
Country: United States
GPS: (36.073868, -103.923638)
Income: $57834 USD
Ahh, to be young.
So any time you lack cross-correlation data (and age vs income isn't a widely available public data source) it will assume the data is uncorrelated, and you'll get this kind of error.
Whether it reduces the utility of the data depends on the use case. I suspect it often will.
I did think that referencing social networks is a bit off, since this isn't a social network model. We have those, this isn't one.