I agree with my friends here.

I would also ask how much lower is the rental compared to market rate and whether there is any good reason for renting it for less if the slightly smaller amount is justifiable, for example, because the there are good reasons to believe that this particular tenant would upkeep condition of the home better than other prospects that may help reduce maintenance costs.

Otherwise, renting the property for less than market value shows a lack of profit motive.  After all, deduction from gross income is only allowed as a matter of legislative grace and not a given.