How did you find these properties, don't you have another one in Vegas with a sewer line blockage 20 feet below and city wanted you to dig it up and tenants had to relocate?

Soil conditions, depth of the line, how long is the sewer to be replaced, will they be replacing your landscaping and planting grass afterwards, the list goes on.One other note, here in Cleveland if the blockage is on the downstream side of the clean-out in your yard it is the county's responsibilty to snake the sewer out (free of charge, well, you pay in for it in your city taxes but you get what I mean).

Its usually the cartridge inside the single handle lever that has a blockage or the shower head itself.Price pfister and delta might send you free replacement cartridges if you call up customer service and they help you identify the model.

I told them they are responsible for blockages. 

They will be back today since this is a bigger job and they might have to open pipes at sink etc. to find blockage.  

He also suggested to me that very regular furnace filter changes will reduce blockages and so improve air flow to the house.

As others mentioned if it has galvanized pipes they can be deteriorated and causing blockages.

@Jon Holdman yes, I think the rodding and roto-rooting is the same thing.I found this article helpful to understand all the blockage issue in sewer:http://www.raviniaplumbing.com/blog/everything-you...Also this PDF from U of KY also have some in depth info - if you want to digg deeper in your research!!

Also, if it's a multi, and the blockage is in the main sewer line, you have no proof it's him. 

But for whatever reason i have this mental blockage in my head that “I am taking advantage of the poor people by purchasing their property pennies on dollar,  I just feel it’s not right”.Can somebody please help me getting over this mental blockage ?