Over the years I've dealt with many PC systems in industrial use - and I can state that the cases shown in the article are relatively clean
I can sympathise with Lee with his farming industry experiences - I've worked in Steel mills, paper mills, and sewage/waste plants and some will actually set a time limit of 3 months and replace the system - as it's more economic than building and operating a positive pressure computer room.
One of the most amazing things I recall was not actually a pc but a remote electro-mechanical switch in an enclosure in Algeria. We knew there was a switch as the system was operating and the switch was shown on the drawings ...
.... We found it after removing about 18 inches of sand from the base of the enclosure