Is it off by a few feet in measurements or is it an entirely different property?

You would prefer the guarantor to own the place where they live and have great credit score (not the so-so scores you'll take from a tenant).The recentness  of the eviction helps in measuring the risk.

It's easier to measure than weighing a pet.

It would be difficult to measure anyway since it's not like an UP-DOWN-UP-DOWN, it's a gradual slope across the floor.

While it may have a measurable impact, the primary determinant of a house's value is location.

I cannot decide if it is wotrh to measure it, could that be a base to bring down the price considerably? 

(Which BTW, those types of measuring sticks may tell you that you won't be getting their attention).

I didn't measure if it was 6 foot. 

If you can measure the size of the house from outside when you can't get inside simply figure the square footage.

@Sam Leon Yep, are you allowed to do any preservation measures to avoid further damage.