I've done the "pre-inspection" for several people who then hired a home inspector who missed every serious issue I pointed out, and caught a few things like cracked switch plates and poorly attached trim, and a missing crank on a casement window - missing the fact that the "redone" wiring was a total disaster and the roof, although it looked good from a distance, was about 5 years past it's "best before date" with serious issues in the valleys. Not to mention one of the carport posts was not carrying any weight because it was roted off under the recent aluminum cladding, and the asphault driveway was almost the consistency of gravel. ( that's just on the latest one) A total waste of, IIRC, $450.
There is ONE home inspector in the area I would trust to do an adequate home inspection - a former building contractor and developer who's been raising a bit of a "s*it storm" in the provincial property inspection circles for several years. Real estate selling agents are not happy when he's on the job.