Plumbing issues, electrical issues, roof damage, foundation issues, infestation, etc. 

The applicant's story was that he vacated the property due to rodent and or bug infestation.

My main concerns are finding areas that are not crime infested slums and areas that have a steady rental market.Anyways I look forward meeting new people and growing my business.

Its a legit answer but guess what, they "forgot" to tell you that there is cracks in the foundation that an engineer told them to fix 5 years ago and its getting bigger, or there is asbestos found in the attic or they have a serious termite infestation.

Pest control can sometimes tell where they started based on the level of infestation. $450 for a 4 unit is a screaming good deal for bed bugs.

The place was completely trashed and rat infested.

Aside from cosmetic stuff like a new coat of paint, the place had an illegal garage that had to be torn down, a backyard infested with ivy (90% coverage, no joke), a potholed driveway, it needed a new furnace, and once my tenants moved in they learned the hard way that the main pipe to the septic tank was cracked and had to be replaced (ouch!).

You need to kill any active termite infestation You need to asses the damage already done.

@Anthony Gayden You may want to read this piece: http://www.insurancequotes.org/home/how-pests-affe...What a lot of people may not realize is that typically in insurance policies, pest/vermin infestation is NOT a covered peril under their policy; due to a myriad of reasons.

Known problems, some water damage on a couple ceilings, bed bug infestation in basement and 2nd floor apartment, back yard is a mess, and electrical wiring is old and designed to support 2 apartments not three so there are frequent breaker "tripping" events.