I usually read the backs of all sorts of domestic products. Listerine mouthwash has a warning on it 'Do not swig directly from the bottle' - why to hell not? Bacteria from your mouth is hardly going to infect a bottle of antibacterial mouthwash!? I need the reasoning for this precaution, incase I am inadvertently creating a Listerine resistant superbacteria - they wouldn't put it on there unless it was important!?