That's using an extreme example. To use a better example, if you have some degree of alcohol consumed, there's a multiplicity of other reasons why you may get a falsely high reading for a small amount. For hyperbole, I used an extreme example, but without some actual alcohol, you're unlikely to get some reading.
Just by way of example, if you were to simply swish alcohol in your mouth—you're not swallowing it, just swishing it around in your mouth—and then spit it out, you would show a blood alcohol level that would be fatal if you were then tested by a breath device. The Intoxilyzer had a slope detector put into it that was to try to help deal with this type of contamination.