Inspectors have been called "expert generalists." Usually they're not equipped to do specialized work, such as checking for termites. That's a job for a pest inspector.
Likewise, you usually have to hire specialists to assess the conditions of swimming pools, septic systems, underground storage tanks for heating oil and the health of trees and shrubs (don't blame the inspector for not detecting a dead tree in the winter). There are exceptions: some general inspectors are qualified to examine swimming pools and septic systems.
Not all inspectors assess appliances, such as washers, dryers, dishwashers, refrigerators and stoves.
Inspectors who are members of ASHI are forbidden to have a professional interest in the sale, repair or maintenance of a property they inspect. They're not supposed to use their inspection business as a way to find customers for a handyman service that they happen to own.