To give you a good example, look at this listing: https://www.zillow.com/homes/f...They got the structure of this house up, then got destroyed on the costs trying to finish it out, and it has sat like this since 2001. it is only 2 stories with a daylight basement.

The whites just get destroyed faster even with bleach and hydrogen peroxide treatments. 

You discover his unauthorized dog trashed the carpet in the living room, destroyed a couple doors, and the entire place needs cleaning.

.  :-)But if you aren't careful and you are overly leveraged (especially if you are using cash out refi's every couple years to use as the down payment on another property), it is easy to see that net worth destroyed by the sometimes wildly fluctuating local real estate market.  

Then destroy it!

A bad property manager can destroy a good investment, while a good PM can save a mediocre investment.

But the reality may be that the tenant hasn't paid in two months, or pays 20 days late every month, or their dog is destroying the carpet, etc.There are literally hundreds of threads explaining the dangers of buying a property with existing renters.

They look good on paper, but the realities of low-quality renters, high crime, unscrupulous vendors, and other problems can destroy the investment value.Some landlord insurance policies have burglary as an additional rider you must add on specifically.

I can't say I am worried he is going to destroy the property as he does not seem angry with the situation however I am curious what those with more experience my offer in advice. 

Takes a long time to build that up even if you can get 20-25% returns.Depending on interest rates (6%) should be able to get close to 20% on turnkey properties provided you keep refinancing to keep leverage in the 4-5x range (destroying your cash flow in the process) Higher returns require value add or getting lucky on appreciation/deal/interest rates.A great brrr should return approximately 100% the first year and then back to the 20% afterwards.