The essential problem is (and I risk being indelicate) that once you get a bit of a belly (even a little one), you can't see your, er, water pistol. Since most of us fondly believe it's rather longer than it really is, we don't stand close enough; the upshot (downshot?) is that when we shake off the drips they don't go where we expect them too (and we can't see where they do go, either).

I think a more acceptable solution might to have two pressure-sensitive footprints clearly marked in the correct position, which will give you an "OK" message when you stand on them, and cancel the "not OK" message.

Or maybe just educate people...?