Calculating Rehab Costs

[Ryan Doyle]

We found a listing  of a house for sale for $26,000 that is in foreclosure (3/2 with detached shop, built in 1975).  My question is how do you calculate rehab costs when the property is being sold sight unseen?  The listing has photos and it looks rough, but if we can't physically look at it, how do we know what will need fixed?  Should a real estate agent give you the appraisal details upfront?