There’s a difference between a blood alcohol content test, which measures how much alcohol is in your system, and a test designed simply to determine if there was alcohol in your system. BAC tests can be unreliable if they aren’t performed correctly, and many people attempt to influence the test by trying to delay or contaminate it.
Tests that look for biological markers of alcohol use are more reliable, but people do still try to cheat them. For example, some people try to get someone else to give the urine sample if that’s possible given the scenario. In most cases, when an alcohol test is required, the testing organization, employer or law enforcement unit has a procedure in place to keep this type of thing from occurring. There are many myths and tips for beating a breathalyzer but most are fiction. Attempting to use mints or mouthwash may cover up the smell but do not actually change the amount of alcohol you exhale. The myth of ‘sucking on a penny’ or keeping one under your tongue also does not hold any truth. A well-conducted test rarely leaves room for manipulation.