It has been my experience both as an investor and a REALTOR "Total Rehab" is a catch all phrase. It can mean anything from just the inside needing work, to new plumbing, electrical, windows, roof, siding etc. The best way to get a good picture of what needs done is to work with an agent who is expierenced in selling properties that need work. They should have a list of people they work with who can give you an estimate of the cost and work needed to bring the property to marketable standards.
I would be happy to assist you with the purchase of properties needing rehabbed. There is no cost to you to use my services. I have contacts who can look at the property bdfore you purchase so you know what work needs to be done. Please visit email me at Todd@ToddOrrill.com for a no hassle no obligation meeting to asnwer any specific questions.