Sometimes clients misunderstand the purpose and limitations of a home inspection. No disassembly of equipment, opening of walls, moving of furniture,appliances or stored items, or excavation should be performed during the inspection process.
The inspection report is intended only as a general guide to help the client make his own evaluation of the overall condition of the home, and is not intended to reflect the value of the premises, nor make any representation as to the advisability of purchase. The report expresses the personal opinions of the inspector, based upon his visual impressions of the conditions that existed at the time of the inspection only. Systems and conditions which are not within the scope of the building inspection include any systems which are shut down or otherwise secured. The inspection and report are not intended to be technically exhaustive.
This isn't to say that all home inspectors are proficient at their jobs, but there is a "Standards of Practice" that we must follow to limit liability. Please check out these Standards at http://www.nachi.org/sop.htm
Hope this helps.