If it is routinely done it does not make sense to do it.

I realized after reading back that I said interest free and it probably raised some skeptical eyebrows.

You can look them up for water and air.An interesting side note, if you superimpose a map of the U.S. showing cancer rates over a map showing radon levels, you will find no correlation.Testing has become routine during due diligence prior to a sale.  

I have routinely seen "$1500 carpet allowance with acceptable offer," on listings.  

I actually have (2) face tattoos (eye liner & eyebrows) and another on my entire right calf.

 We started routine semi and quarterly inspections after a similar situation and it's been a great way to stay on top of things and build a better relationship with tenants.

I routinely runs quotes with most of the markets because there are often large differences between programs rates and which will be most competitive differs from property to property. 

While anything is possible and a carpet cleaning job could potentially take multiple days to complete and involve large fan/towel/dehumidifiers, I would suspect it would be less probable it was just a routine carpet cleaning. 

If you're going the umbrella insurance route, make sure it will cover you for several things including just the routine slip and fall (like mold or earthquake).

That gives you your routine expenses for a long term rental property and assumes a nominal amount of vacancy.