During an earthquake the house became damaged and new city ordinances prevented them from rebuilding the house and they still owed on a mortgage for the property so they were on the hook for the mortgage but could not use the land or live on it anymore.

those ozone machines have done wonders on some fire damaged houses I have bought.

They may cause damage if they become bitter.

I am not paying for trips to the property, for unwarranted complaints where damages caused are due to tenant negligence or in this case, no damages or repairs were found by the service repairmen, yet a service call was billed to me.

Most times you can't get into the house, you see the outside but not the inside, which could have a lot of surprises, like mold, water damage, vandalism, etc.On the other hand, sometimes there are bargains, that the banks for what ever reason set a low minimum, then if there are not a lot of competitive bidders, you may end up with a good deal. 

The previous tenant had done some damage to the floor and walls and the back yard was a forest!

It will be very difficult to try and maintain a property across the country and get quality tenants in the property and verify that they are not damaging the property.

Long term appreciation is about it as well as the principal reduction and that is going to take time to be worth the brain damage and risks.All you might have is rental income.

Lucky for me they were in the crawl space and didn't cause any real damage!

What I did see was a water damaged spot/couldn't get close enough to see if it was wet, where the back porch balcony is.