The purpose of guttering is to collect rainwater off a roof and send it away from the house. Inspecting the gutters is a part of a general home inspection.
The first thing an inspector will check is the downspouts. The downspout sections must be solidly connected to each other and to the building to hold the heavy weight of the water running through them. The water flow at the bottom should be diverted away from the building. The NPI inspector will walk under the guttering to observe if any seams appear to be broken.
One of the biggest problems with guttering is the attachments to the house. The inspector will check for sagging gutters, loose gutter strapping or spikes, and clogged gutters. The inspector will note any concerns and recommend repairs.