I would like to see Snopes take on this one. Reported on line as being used in Los Angeles, I have actually seen in in Melbourne, Australia.
I couldn’t believe my eyes as I walked down a nice suburban street, with single homes, each with a neatly manicured front lawn – each with a plastic Coke bottle, filled with water, standing at each corner. I asked my cousin (a native) what in Hades was going on and she just shrugged and said nonchalantly, “yeah, keeps the dogs form crappin’ on yer lawn, dunnit?”
I BEG you to run a scientific test of this and let us know if it works.
[Update] after a little research, Docotr Greenfingers attempes to explain it:
Ever wondered why people put bottles on there lawns? You may have
been told its to keep cats away and its true. But does it work and
how? First of all we must half fill a clear plastic bottle with water
.( Its very important to fill half full of water. ) Put lid on and
place in the middle of the lawn. If you have a big lawn then put a few
about. Leave out and see if it works! Cats are suppose to be scared
away by the bottle, but how you ask? It works best at night and if
there a breeze. Take a light say from a street lamp, car or one of
your windows. This light travels through the bottle and the water
which is then reflected away like laser beams in different directions
giving off little flashes. The cat sees these flashes and Zap! He's
away. There you have it so go out and try it out on your lawn.
OTOH, Cats Away declares it to be a myth.
And the Snopes jury is out - undetermined.
Please, for the sake of humainity, you have to conduct experiemnts and report back to us.