The biggest hurdle is the human element.

Unfortunately gang ,there are "cocky and arrogant" individuals in any ,practice,trade,endeavor or profession.Plumbers with a disagreeble arrogant and surly nature do not last long where I come from.It is highly competitive here in So Cal.You gotta be a "Superstar".Having said that,,,there is also a Code of Honor amongst tradesmen in any town or city.We all know who the good guys and the bad guys are.The bad guys are "disowned" and get put on the blacklist,,,they do not get referals or reccomdations from reputable contractors.We also watch them very carefully and inform our friends at the supply house,,,,do not give these guys credit,do not recomend them,,,they are trouble.We know "The Good,The Bad and the Ugly".But get this,,,good guys tend to hang together and refer each other.They also tend to join credible contractors associations like the PHCC Plumbing Heating and Cooling Contractors Association.Heres a tip ;if you are fortunate enough to identify and hire a good licensed plumber,he will usually know and be able to recommend a good electrician,HVAC man,carpenter,tile setter,painter,concrete and masonry contractor,locksmith,roofer,landscaper,,,you get the picture,,,,Oh Yeah about that business of "plumbers savings lives".Well,,,That is a true statement,,,,that fact is,,,"Plumbers have saved more lives than Doctors,,,,"An old American Standard slogan was "Plumbers Protect the Health of the Nation",,Well,,,Its kinda corny guys but it's TRUE,,,,Why ?

Aspects such as Human emotions and issues of  undercapitalization will let a more logical, well-capitalized and analytic investor profit from the inefficiencies and hence can control the outcome.

They aren't going to lend on a crackerbox that has health and safety issues or significant deferred maintenance.

However, if she is getting up in years or has health issues and she is disposing of assets to qualify for medical benefits, a Trust won't help her.

Being around her leads to anxiety attacks and just overall deterioration of health; it's like living with a soul snatcher (lol).

The more you delegate out via contracts for service, the better your health and satisfaction will become. 

I'm not sure which National Group you belong to, but ongoing education, association fees, equipment costs, advertising, health care, insurance, taxes.

Per CA Civil code - and you should look this up - (12) Infestation of insects, vermin, or rodents as determined by ahealth officer or, if an agreement does not exist with an agencythat has a health officer, the infestation can be determined by acode enforcement officer, as defined in Section 829.5 of the PenalCode, upon successful completion of a course of study in theappropriate subject matter as determined by the local jurisdiction.Did your tenant have the "vermin" looked at or determined by a code enforcement officer?  

I don't see how it will make any difference assuming the water tests safe depending on your local health department guidelines.