Also if you are not going to scale up, it doesnt make sense to be an OOS landlordwhen I thought I wanted to be king of the C class rental world and bought 350 of these.. one thing I did prophylactically was I replaced the waste line on all our homes during initial rehab

Think of the ceremony as a prophylactic. 

Remember sewer wont back up with just a home inspector flushing the toilet a few times.. it backs up once the home is occupied and EVERYONE is using the toilet and washing cloths etc.this is what I would do to protect my investment probably cost you a grand or so.. or just forget it and take what they give you but realize you will probably have some severe cap ex in the future. because these things wont be done prophylactically..  

There were syringes and prophylactics strewn about.

My brother in law in the Bay area does them every week.. as in some cities in the San Francisco bay area if the house is of a certain age and the waste line has not been replaced its mandatory to do that prior to transferring ownership.. nice deal for him realtors have him on speed dial LOL.but when I used to buy rentals and rehab and rent.. the very first thing I did was replace the waste lines while we were rehabbing.. its the number one thing that goes wrong in a rental. and you could lose good tenants over it.. no one wants constant plumbing issues.. so if it was not PV we just fixed it prophylactically so we limited our NUMBER one service call plumbing.  

Tenants are unhappy your unhappy the fix has to be done as an emergency.. much easier to do this at rehab and about half the cost then a emergency repair.When we bought our rental pool we prophylactically replaced all sewer lines unless there was clear evidence of a new PVC line.And the last person you want to count on or who would even have a clue as to the rehab etc is as Petra pointed out a west coast bird dog.. they just introduce its up to you to do proper due diligence and inspections.

WE prophylactically replaced the sewer line from the home to the street if it was not PVC  IE clay pipe that gets clogged.

@Andrew Syrios  when I was buying low end cash flow homes in the mid west... unless there was a PVC riser we replaced sewer line prophylactically.

To carry the analogy further, fire departments are usually better positioned to engage in various prophylactic measures as well: inspections, prevention, education.  

If the waste line was still clay we replaced it prophylactically, the reason being we could get a sewer line replaced for 1 to 2k during rehab ... as opposed to having an emergency replacement with the tenant in the home and that costing 3k or more