As far as riding style is concerned, dragging the rear brake is a legitimate riding technique. I commute through london every day, with lots of tight 90deg twists and turns on my route. Dragging the rear certainly makes the bike *feel* more stable on a slow tight turn and dampens the jerkiness of the throttle.
Its not needed on faster corners.
This is my riding style, works v.sucessfully for me, so if you don't like it - fek off