polo2k wrote:simple solutions to this problem include replacing your main beam bulbs with a xenon kit, aiming your headlights too high and then making liberal use of the left hand stalk behind the wheel on every opportunity

This is all very true, but I find that the vast majority of fog light offenders fall into two categories;
a) women drivers doing the school run, who didn't even knew they had fog lights in the first place so aren't going to know what the hell your flashing them for - they just press all the buttons that look anything remotely like a light when they get in, but really haven't got a clue what they do.
and b) 'just passed their test' baseball cap boy racers, who are driving 1.1 L reg Vauxhall Corsas with tinted windows, three spoke alloys and blue leds on their washer jets and can hardly understand english, let alone the subtlety of a headlamp flash
Still anything is worth a try!