Research the property for liens and such before you think you're getting a smoking deal.And as @Joel Owens mentioned, there is no telling what real problems this house has until you open those walls.

Holy smokes if you guys actually think snail mail is even worth a fraction of targeted FB ads I have a fantastic business opportunity for you guys to invest in! 

I inherited a tenant that smoked with a building that I purchased.

One has to have a strong bs detector in this business, I think. 

For this size apartment,, 4 people in a 600 sq ft apt,, would be like packed like sardines..I always set my occupancy well below the standard.. my 1 bedrooms were limited to single person occupancy..2br's 2 people,, studio's 1 person.. and no pets..and no smoking.. 

Landlords have a right to inspect to make sure the smoke detectors are operational (this is a requirementbin all states that I know of) and the property is in a safe and livable condition.

If it's clear you are not blowing smoke, are pre-approved and have the ability to buy then there should be no issue with showing properties.

I'll paint oil-based Kilz on any exposed char or smoke damage post demo, add new HVAC and plumbing, do a complete rewire, install 3.5 new baths (only 1.5 are new; others will be re-dos) and a new kitchen. 

I would recommend you start by downloading your landlord tenant laws for your state..Then set your rental criteria,, credit score, income, (= to 2 or 3 time the rent ), occupancy limit per bedroom size of apartment... no cosigners,No pets,, no smoking,, what ever..but it stays the same for everyone.. 

Reject them because of their hygiene, or because you were unsatisfied with their references, or they smoke.