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According to "ESRI Shapefile Technical Description An ESRI White Paper—July 1998", Vertices for a single, ringed polygon are, therefore,always in clockwise order. Otherwise,"Dirty" polygons occur when the rings that define holes in the polygon also go clockwise, which causes overlapping interiors.
In my understanding, you can create donuts polygon with "avoid intersection of new polygons" is checked on snapping option, even if both polygon(inner and outer) are created clockwise roated.
It has not necessary to care about clockwise rotation when you create polygon in QGIS.
Is this a right understanding?