In the 1950s, engineers at the Massachussetts Institute of Technology built a massive tank with a small plug-hole. They filled it and left it to settle for several days, then opened the valve. In each of the many repetitions of the experiment, the water DID start to swirl in an anticlockwise direction. When they deliberately set up a clockwise swirl, it invariably died down and returned to anticlockwise. The explanation, apparently is that - if the water has settled completely - it is rotating, along with everything else on earth. The fluid particles nearest to the equator are obviously moving more quickly than those furthest from it and, when they are released, they develop their characteristic direction-finding properties.
As regards "ordinary" plugholes, it's a myth.