I went through a divorce that bankrupted me and left me with all the marital debt (nice combination).

Tenants will have marital problems from time to time. 

This is what is on page 1 of the application:Our Criteria:We do not deny housing for race, color, religion, sex, national origin, handicap, sexual orientation, marital status, or familial status.We do deny housing to individuals: when the application is not complete or accurate where there is not sufficient income/resources to pay rent and livewhere there is poor prior tenancy: evictions, violations, damage to rental property, poorly handled move outs, amounts are still owing to landlords or utilities.Criminal activity is at our discretion depending on severity, number of convictions, and how long ago.In your specific case I would deny them for having a prior eviction, unless I could reach the landlord and determine that they complied and have paid amounts owing.  

I was under the impression that the net passive loss allowance phaseout begins at $100K MAGI and the phaseout is complete at $150K MAGI regardless of marital status.

It should have been a red flag when I saw his typed list of questions regarding property location, loan amount and private information like sex, race and marital status.  

However, if you're describing it as "caved in", that would signify a problem. 

The contractor had his wife waive her marital rights  to the property.

Discriminating against people because of marital status is breaking the law.

My state is Missouri, Can someone please explain to me the advantages of signing a marital waiver vs the spouse being on the deed of trust.

Also look to state law as to your marital interest, but in many instances, inherited property is separate property.