Could it just be humidity and if so how can I remedy this? 

then U have the weather  oh man the weather  LOL.I lived in Palo Alto for 8 years and many said that was the best weather on the earth.. not to cold not to hot No humidity etc etc..

I recently sprayed down the whole basement with concrobium “mold killer” and tried to keep the humidity levels down because that’s the only way concrobium can effectively kill the mold.

It monitors temperature, humidity, light, sound and motion.

An unvented crawlspace, if not air conditioned, will most likely be a nightmare, especially in hot humid climate.

I can see humidity being a complaint after it rains here, flooding I'm not so sure..

I think there might be high humidity in the basement area where they are installed and that they could fail prematurely as a result.Financial Summary:I am putting 25% down and will be securing a 30-year fixed mortgage.

Just go cheap on toilets or clean existing.One inexpensive technique I've been using more lately (even in bathrooms) is Board & Batten on the walls or "shiplap" look with MDF 1"x 4"s (oil based primer for humidity protection). 

The tenant expects to have me fix the vanity and blames the damage on the humidity in the bathroom since the bathroom ceiling fan doesn’t properly channel the humidity out of the bathroom.

Each has their difficulties and differences, but generally the easiest area to grow is the High Plains (deep sandy loam soil with calcareous base, hot days/cool nights, flat topography, low humidity, good groundwater and rainfall).