We believe that we will attract undesirable tenants who are willing to rent a unit that is not clean.

I am familiar w/ Olmstead - that makes a single member LLC undesirable for me. 

When did $100-$300 of free cash flow per month per property become undesirable? 

Other lease items the tenant will not want to change can make a property undesirable even in the best of locations.It's all about the lease, the tenant, and the location.

If you don't use a contract you are more vulnerable to an undesirable result.You can find some contracts online, but beware they are thorough and valid in your state. 

You might want to think about the resident turnover differences there are in your area with each system.To me, PTAC would be a low class C resident, and still I'd wonder about the turnover (in some instances).If I were looking at these options, I'd look at "Service Life" + "local Maintenance and Repair" compared to intended length of hold for the property, as well as resale value (un-desirability) with each type, and the ability to command market rate rents.Good Luck!

Raising the rent too high could lead to undesired confrontation and may be difficult to find tenants moving forward if the current tenants choose to find housing elsewhere.

That weeds out most of the undesirable.

It’s important they understand they’re selling an undesirable situation and should fact that in their sale price.

I plan to buy my first rental soon, and I thought a 6 month lease might help ease the pain of having an undesirable tenant.