Many zoning laws cover items such as density (dwellings/acre), lot coverage (building area/lot area) or impervious area (house+paving area/lot area) all of which could have been violated by someone just going "wild west" on the lot and building homes there without subdivision/zoning approval.Zoning Ordinances and Planning Ordinances are usually online these days and the County/township/city will have a record of any applications filed for building a new home on the parcel.Just a word of warning that a seller might not want you rocking the boat if the structure is non-conforming.  

@Eddie Lehwald If you are going for cashflow I would look at San Antonio, Kileen, or Round Rock/ Pflugerville.

Sounds like you've definitely found a niche and are rocking it out.

In LIttle Rock, we utilize section 8 and it works great.  3.

I was in Dallas a few weeks ago and you could throw a rock in the air and it would most likely come down and hit a self storage business.  

Here is what I judged the noise level on,Inside if I'm standing outside the closed apartment door and can hear loud music, in the hallway, it's too loud.If I can stand outside the building and hear noise it's to loud.

I have cash buyers and my title company ready to rock.

I actually laughed out loud. 

If the ground has rock in it that needs to be blasted that can raise costs versus regular dirt.

If he really is licensed, inform your secretary of state/licensing dept. and find out if you have recourse against his performance bond.Your best bet after that would be to then sue him for liquidated damages due to his failure to perform (Your time and trouble, the cost of the other contractor) ... bear in mind that if he doesn't have a bond, this may be like squeezing blood out of a rock... cost you more in legal fees than you can possibly hope to recover.