Is olfactory detection of methane/natural gas odorant the only reasonable method of discovering gas leaks when the connectors are not accessible?
Pursuant to Section 535.227(a)(1) of the Standards of Practice, inspectors are not required to move appliances in order to inspect behind them. However, it is often possible to locate gas shut-off valves either behind or near appliances (such as in the cabinet next to the range). If a gas shut-off valve cannot be located, this should be reported. As the question suggests, it is sometimes also possible to use a digital camera to “see” in areas that are not otherwise accessible and there are multiple means of detection of gas leaks in existence, such as through the use of hand held detectors (however, these would be considered specialized tools and are not required to be used in performing inspections).