We are changing the carpets in the home and come to find out, the dog has probably peed all over the carpet in the past causing the pad underneath to disintegrate.  

A lot of these homes are older and your on paper 2-3% rule can easily disintegrate with capital expenditure and/or eviction/turnover. 

Even the great tenants who are always on time don't change them or if they did it's when you remind them the third time after 3 months...I would give them 12 filters and at the end of the lease there are still 11 new filters and the original one completely disintegrated and become "mush" on the coil above it.So now I always change it every 30-45 days myself, and use it as a way to do a quick inspection of the property.But too many odd size filters for each property or each individual unit is a real pain.

If you think you are reusing them, and they end up disintegrating upon removal, who quickly can the gutter contractor get out to replace?

I can't discern in the pictures of the sources mentioned if the brick is disintegrating or stair-stepping. 

We made sure our gutters were always cleared and have leaf blocks over them.When it still continued, my contractors noticed that my neighbors gutters were blocked and that there was a 4" by 2" by 2"  hole behind the gutter where the wood or brick had disintegrated. 

Old houses have cast iron pipers that will disintegrate (because of age and/or foundation shift).

Old houses have cast iron pipers that will disintegrate (because of age and/or foundation shift).

Extreme care must be taken to ensure the tar/cloth crap remains or at the very least, does not disintegrate up, into and behind the metal jacket that encases both wires.

Old houses have cast iron pipers that will disintegrate (because of age and/or foundation shift).