Multi-Family Deal Possibility - What am I missing?

[Mary B.]

This is the first deal I've seen in my area that comes close to the 50% and 2% rules. I just feel like something must be wrong for it to be such a great deal.

10 unit ranch style apartment building (6) units 1bd/1ba (4)units 2bd/1ba
Asking price $155,000
1bd rents for $300 2bd for $400 - Total $3400/mo

$155,000 X 2% = $3,100

$3,400/2 = $1,700
$155,000 at 5% over 30yrs = $832/mo payment
profit = $868/mo

Owner will finance. Brick built in 1982. All units recently have ceramic tile put down everywhere. Baseboard heat.

Red Flags:
1. This property is in a low income area. I had previously decided not to landlord anywhere that I would not personally (hypothetically) live and this would not fit (My other property is in middle class hoods).
2. I spoke with the owner who stuttered and seemed ill at ease on the phone.
3. Upon looking at the online deed records, I discovered she only bought this place 2 months ago and is already selling.
4. When I google this address, I discover it has been listed on loopnet for sale in 2008 and in 2010 and in 2012.

What is wrong with this property? Why would it change hands so frequently? Would a management company refuse to lease it due to the neighborhood? How can I be sure it has not been a meth lab in the past? (This is my worst fear as a landlord). Any words of wisdom are welcome.