You really have to decide your role, arms length ,., etc.  

Advisors often recommend holding periods of 12, 18 or 24 months in order to help demonstrate intent to hold for investment purposes, but it is the intent that is critical and not the length of time that the property is held. 

As for length of time, I add 10% to the rental rate for month-to-month lease carry-over tenants. 

Measure the length of the outside walls.

.), when your investments are passive - all gains and incomes will be sheltered from taxes.When investing using an IRA all transactions must be "arms length".

Be very careful, as you'll be signing an Arms Length Affidavit saying the seller is getting no money and there are no side deals.

And if the rehab is going to take any length of time, there are holding costs - property tax/elec/water/gas/insurance...

This is especially important if you plan to buy and hold for any length of time. 

Housing agency personnel go to tremendous lengths to enroll only the most responsible working families into the rental income property program, families who truly want to succeed.

The lender wants to get rid of the house, but they wnat the highest amount they can get for it.If you are able to prove to the lender by your research that the house is not selling, the conditions in the area are effecting the value, that repair cost are expensive, that the length of time on the marker has been extensive, that the likelihood of them making money on this house or their ability to sell this house is slim to none, and that their BPO is inaccurate and at best skewed...then you have empowered yourself in such a way that they highly consider your offer.