Why do you only mention ASHI? There are several other home inspector societies out there that are the same as ASHI and quite frankly, some are even better. IE: they require stricter standards for the inspectors!
There is nothing wrong with ASHI, but having always believed this is a nuetral based information site, I am surprised there is no mention of others, or at least a mention that there are others?
Locally, several of the "good old boy" home inspectors are ASHI members, they don't comply with hardly any of thier standards, these guys are in and out of a 2500 sq/ft home in minutes, no attics, crawl, or any other detailed areas are inspected. More of a "need this just to satisfy the bank" kind of inspections. There is no one at ASHI or any of the other societies for that matter that are following inspectors around to assure they are doing a thorought job.
I recommend to people to get online and look for ratings, such as Homeadvisor or Angies list provide. Also, ask for references from past clients, etc..