In my opinion an IR evaluation is not needed for the typical 'visual' inspection of a property related to a resale. It can however be very usefull for more complex building evaluations related to water penetration, air leakage and so on.

Like any complex technical tool though, its utility is only as good as the skill level of the user and in many cases an IR camera is as likely to get the user into trouble as it is to keep him out of it. Accurate interpretation of result requires training and experience.

An IR camera may one day become as common to an inspectors tool bag as a moisture meter is today but that day has not come yet.