You can find a dozen sources for questions to ask your home inspector. Let me add a trio that most lists won't have.
Do You Have Relatives Worrking in Real Estate?
The answer may well be yes. Our region has a surprising number of inspectors who have close relatives working as Realtors or other related industries. In an ideal world, this would be disclosed whenever a conflict may present itself. In the real world, things are more gray. Ask. If the spouse or siblings aren't involved in any way, great. If so, you know and can make your own judgment.
Do You Perform Repairs for Concerns You Find?
Most inspectors will answer 'No.' Most, but not all. While I was still on the Home Inspector Advisory Board, I had an inspector call to complain about precisely this conflict in the Tri-cities area. From the rumor mill, it's happening in just about every region despite the fact that the Washington standard prohibits work-for-hire for one year post-inspection.
Your inspector should not have a financial interest in finding concerns. The inspector's job is to observe and report, accurately. That's it.
Does Your Inspector Follow One Standard?
This seems like an odd-ball question since inspectors obviously follow a standard. The complication comes in with the fact that most inspectors in this area work both sides of the state lline. Washington State has a very well-developed Standard of Practice. The problem comes on the other side of the line. Idaho has no requirements, so some inspectors use a different standard there.
I recently saw a seller blind-sided because his inspector two years ago failed to identity a potentially hazardous electrical panel. Why? Because it was not require in Idaho though is was in Washington. He knew the panel had a lousy reputation and failed to inform his client.
Your inspector should use one standard, the most restrictive. Here, that's the Washington SOP.
So there you go. Three extra questions to ask. It's okay to spend time on the phone with an inspector getting a feel for them and the way they do their job. Take you time, ask lots of questions, and good luck with the inspection.