Underwriting Value - Market Rent or Contract Rent

[Kyle Majors]

Hey BP, 

Just had a thought as I was reading through several appraisals that I found online. 

When underwriting a property I've been taught by @Michael Blank to apply rules of thumb for expenses to the T12 income and to then apply the market cap rate to find a reasonable price to pay.

While looking through these different appraisals I have found online, the appraiser uses the market rent (not the T12 rent) and typical expenses/vacancy to come up with a NOI.

NOI/Cap rate = value...So if an NOI for a specific property is achieved by higher than normal rents, I thought the property's valuation would be rewarded and be higher. And not be discounted by applying norms of that market. Should I be underwriting potential acquisitions with typical rents and not with the T12 income? Can someone provide some clarity?

Thanks BP!