Was the garage conversion legal?
Again, as an investor, if I am buying a property for the sole purpose of earning money, I don't care if the garage is not usable because I would be making more money with it converted to a bedroom. To investors, a bedroom is worth more than a garage (at least in my market area).
It almost sounds like you are combining the sales comparison approach and the income approach. They are 2 separate approaches to value.
I am not trying to be critical and thank you for having this conversation with me. I started this thread to have this exact type of discussion. Most residential appraiser's don't look at an income producing property the same way an investor would.