Tenants will call if the toilet isn't flushing properly, but they don't call about water intrusion until the roof is failing.  

If you don't fix the moisture intrusion problem, it will come right back, even through KILZ.

It seems that municipal garbage services would be intrusive big government at its worst; the thin end of a socialist wedge that would deprive the citizens of their right to choose which noisy truck lumbered up to their house on a weekly basis ;)

Based on above, it sounds more like you have just not treated this as a business, so it might be best to agree to pro-rate rent to the last day of occupancy and return of keys, and simply consider this the cost of a lesson.Obviously I know nothing about your particular house, or the flash floods you have experienced, but why would you, apparently, do nothing when you have water intrusion?

It’s still costly to replace, but the vertical drops would be pretty intrusive. 

This is usually where I have seen water intrusion come from.

How intrusive is the installation?

I would say 90% of water intrusion (other than leaks) is from missing or improperly installed gutter systems

Seems intrusive to guests.Why not just get the person who booked info from booking site?

Beyond the obvious concerns, a deep background check seems overly intrusive.