Well ... Firstly, human lives are much more important than a preference to use an alcohol-based mouthwash (considering that non-alcohol alternatives exist). Sec

Well ... Firstly, human lives are much more important than a preference to use an alcohol-based mouthwash (considering that non-alcohol alternatives exist). Secondly, it very well might be possible to design and/or calibrate sensors to distinguish between both cases based on chemical components or relevant concentration ratios that are specific to mouthwash formula.