What is the oldest house you are willing to buy?

[Daniel Sanchez]

Howdy BP Forums, 

I am analyzing deals in my area and obviously, the older homes will be cheaper but I had a question. What is the oldest home you are willing to buy? I know it is highly subjective to the property's condition but does eliminating houses beyond 30, 40, or 50+ years old immediately remove a headache down the road? What should be a good rule of thumb on age?