Actually I don't really see how this will work. If you are in a
group, chances are you will trust them and people do lookout for
each other, can't imagine someone spiking a drink in front of the
group. Unless the whole group gang up against you. In which case,
you need to be more selective of your friends instead of buying a
test kit.
If you are alone with your partner, you wouldn't test the drink
right? If you don't trust him, why go out with him in the first
place.
If some stranger guy offer you a drink, if you think he is cute,
will you take out your tester and test in front of him, chances are
not as that will be a big turn-off. If you are suspicious or
dislike him, you will probably not take up the offer...
