My observation is that bad properties can sell quickly at inflated prices in a hot real estate market. 

In the short-time that I have been here I have observed two trends in the rental market:1) The city is expanding outward with such pace it is unlike anywhere I have seen.

Here are some general observations:-Is there any specific documentation that I should request for the damage of the property, if so- who from? 

@Nick UhasWell, here's my observations/advice given what you shared:Unless your dad was a big fish and had operations that actually justified having 4 houses untouched and vacant that needed work, (I'd guess that to justify this level of stagnation, at any given time he'd need to be turning over 15-20 projects per year) - the takeaway from this fact was that your dad didn't have the understanding of cash flow/ value of money to motivate himself to get the projects done in the proper order (ie: finish one, then move on to the other etc).I mention this because you need to learn the lesson he did not, which is that you have holding costs on these houses and you need to get them done ASAP. 

Two quick observations. 

@Anthony Dooley What % of rental income do you typically observe in the area where you invest? 

If you talk to five different people you may get five different opinions and observations about their mortgage.

Hello,As has been my observation, a normal application fee is 20-25 dollars.

I have no experience with commercial properties, but from observation i can say... small companies tend to stay in their units much longer than a renter would. of course there is the exceptional few 'dream renters' who take good care of your house and stay for years upon years, but for the most part I believe you will see 5, 10, maybe even more come through a residential rental in the time that you would see 1-2 through a commercial rental.I can name a number of small shops in my town that have been renting the exact same units for 20+ years.

Eric, I've come to a similar observation as I've run the numbers on prospective properties.