Years ago: I knew of a couple of offshore oil support operations that required everyone, including passengers, to blow when reporting to the hangar. If the test was positive they required the immediate removal of the person from the contract with no confirmatory further testing. The criteria for a failure was very low, < .02 or somewhere in that area. (apparently someone can blow to that level having not consumed any alcohol) This caused a number of folks having to leave the contract and damage to their reputation.
Someone googled the equipment being used and it was obvious the oil company at one location were not carrying out required calibration and maintenance of the equipment causing false readings. As an example there was a requirement to change a filter after 100 uses. This simple thing was never done.
The reply to entreaties to carry out proper procedures and maintenance was a roaring silence. Hopefully things have much improved since then.