This one's for Larson, why I don't recommend humidifiers part 2

From today’s inspection - new home
Outside temp -17 C 2 F dewpoint -27 C -16F
Humidistat set at 75%
Humidifier, inspected in September 2013 already starting to calcify

Well I guess your clients are too stupid to read.

You need to find better clients.

You may be right about that, anyone have a pre-inspection IQ test for weeding out stupid clients?