"Nobody has ever really done a serious examination of the record on this with things like crop circles. " - Actually they have- The "researchers" have been shown for what thay were often.
But the nutcase crop circly advocates get more press, and- as we have seen here- the lunatics are certainly vocal.
There have been cases where crop circles have been made by people using simple methods, then the "researchers" come in and find 'proof' that no human could have made it- They try to use scientific jargon to describe their work and fail miserably, they succeed only in demonstrating their complete ignorance. 'Earthfiles' run by lunatic media whore Linda Moulton Howe is and EXCELLENT demonstration of the ignorant garbage these people turn out and try to market to other lunatics and the terminally gullible.