Occupants create moisture just from their bodies, not running exhaust fans in the shower, cooking without venting and humidifiers.

I don't know how much rain you guys get but the owner had a large de-humidifier he had been using for over a decade and claimed was sufficient except when they had a lot of rain.

I have two de-humidifiers to help out with that.  

The wholesaler mentioned the sump pump broke, which explains the puddle of water in the basement in the photos and the humidifier, but on zillow I found a note that stated "the homeowner had major problems with sewer and flooding" which obviously sounds a bit scary. 

Do not buy them a humidifier!

Our contractor had to remove the water, remove the carpet and vinyl, set up box fans and humidifiers to dry out the area and install new sump pump.

We're going to let her stay for a bit and feel it out, but I like the humidifier ideas.

Constant calls with nonsense such as my cereal is stale and Its the landlords fault because the humidifier isn't good enough or the cat next door meows too much or the handyman smells.

An A coil freezing up has nothing to do with a humidifier.

I always remove washer/dryer, remove water softener, remove house humidifiers, block off fire places and never install a garbage disposal.