The most annoying ones for me are on westway near acton in London. A group of eastern europeans are constantly at the traffic lights, trying to get a few quid for spraying fairy liquid on your screen and giving it a wipe. They basically do the exact same job as using your washer jets/wipers for a few seconds. The main annoyance is that they don't leave you alone, even after turning on your jets to try and get them to **** off after they've drawn a heart or some crap on your windscreen.