Its market and local code dependant for all other then the (in my view and most code) the GFI's in the bath, kitchen, exterior/garage/basement outlets.Buying an older house has more expenses vs post 1970 which is when most systems are all up to snuff;  plumbing is largely copper, decent circuit breaker boxes and amperage power feeds from the street, sewer largely PVC...   

I would consider the following (which you may have already done):House rules say no gatherings (penalty of $X per person if violated)House rules say quiet hours are 10:00 PM - 8:00 AMIf profile has no reviews / not verified, require they confirm the # of people who will be at the property & agesUse a noise monitoring system like Minut or Noiseaware (disclose in listing)Use exterior cameras to monitor driveway (disclose in listing)But at the end of the day, there are still bad guests who will get through and sometimes you just have to file a claim, kick them out, apologize to neighbors, and get the place ready for the next group.

I didn't realize we were walking into such outdated operations or I would have prepared my own system.

Developing systems to source solid off market deals will help open doors to other things you need to ultimately be successful.

This will be pricey in the end because you are slowly killing the compressor as home AC does is supposed to be a sealed system.

We are near the world's second best hospital system.

He shares his systems and processes to find deal finders/wholesalers, real estate agents, lenders, property managers which he calls your core four.

When were the major systems and structure components updated (HVAC, roof, electric)Once you answer those and are comfortable with the answers from the other guys questions, you should be good. 

This is going to always be a work in progress, as I’m trying to overcome 28 years of living a life thinking I’m the most important person in my life. 2) Put routines and systems in place that keep us on track for our goals, and correct us when we start veering off. 3) For the first time in my life Scripture study and prayer is a habit.4) Spent more time with family in the last 10 months than I probably have in the last 10 years combined. 5) Grew our rental portfolio from 1 property to now 8 properties.

If they knew what they were doing, their initial questions would be about the services offered and systems in place to deliver those services consistently!