What's the possible legal issue that can arise in the future if landlord keep turning a blind eye, not adding frequent Guest as co-tenant?

They frequently miss their own deadlines.  

The outcomes of greed are often not as easy to diagnose.The tenant moved out and in resentment of the frequent rent increases, completely let the place go in the last year they lived there.

@Christopher Lugo Find mentors and communicate with them frequently.

The contract will frequently include more information than you necessarily need for every deal.

New buyers frequently complain about how this is "unfair"...until the value of their property goes up (at which point you don't hear a peep LOL).The good news is that no matter how much the market value of your property goes up the tax only increases a max of 2% per year,meaning that Year 2 your tax won't exceed 1.02% of purchase price, third year 1.04%, year 4 is 1.06% etc. 

I have one myself.However there is NO EFFING WAY I’d ever buy an investment property on septic unless I was definitely replacing it with sewer lines to the city.You can really mess up the tank and require more frequent pumping based on what you flush and tenants aren’t gonna be careful about that.

I ask for private money frequently and have found this to be relatively easy with a good relationship. 

You could do more frequent inspections, but never expect your rentals to be the same as your personal home.

In any case, do more frequent inspections when animals are in the home and charge for damages as you discover them.