The roof on our two story home is 15 years old, 3 tab asphalt shingle.

Ice forms and expands under the first layer of shingles. 

A roofer sees step-decking and waits until all shingles are off the roof to tell the the owner that they need another $5k to replace the decking with plywood.

Don't look for computerized stuff till you understand the basics and don't buy any property until you know how to analyze the numbers and tell a deal from a dog. 

Some places will not insure a home if,as an example, it has two layers of shingles on the roof.I would be up front with the lender and up front with your insurance agent BEFORE you even commit to a formal credit check on a loan to get answers.Fannie Mae also has some really strange rules you might have to abide by...talk with your lender.

A metal or flat roof is going to cost more than a truss roof with asphalt shingles. 

Essentially the seller is saying: my street is so bad, I will sell you the house for a fraction of the cost it would take to build it, maybe for less than the lumber, shingles and windows would cost.

Final result is new roof (shingles and sheathing), new paint, new countertops, and new bathroom.

@Justin Stanfield,   Good call on the roof, I missed the part where it was going on top of the shingles.

They had asbestos shingles, propane gas for washer/dryer/stove, oil for heat with 50-year-old burner.