What can I do to prevent a big problem?

Do you know if an unpermitted structure would actually prevent title from issuing extended coverage? 

Based off the photo, it appears the parking area is also in the front, which as part of 'Tenant Proofing' I would add some sort of railing or fencing to prevent tenants from parking too close to the property.

These are all great real-life examples of why we need to do all we can to prevent rent control from coming to Alberta

I would consult with a local attorney about what types of pre-payment penalties (if any) are allowable in your state specifically. this would potentially prevent you from going into this with the expectation of 5 years of payments (for example) only for the buyers to refi next year and you've now sold your property AND get no monthly proceeds from the lending side. 

I recommend that you tighten and then use crazy glue or JB Weld to prevent them from working loose.  

It prevents you from seeing the roof and the ground around the property, sometimes you cant tell the condition of the concrete driveway.

I could have prevented this by having the plumber run a camera down the lines.

They do not realize the cash flow requirements of a particular property, which vary dramatically based on age, amenities, actual physical conditions of every common and limited common element, current quality standards of the Board (which would include proper, regular, preventative maintenance on MANY elements), and the motivation (or lack thereof) of the Board.

That still won't prevent her from going to the house.