I've never heard that one, other than the pink and moist vent.
You can put your fingers between their pelvic bones BELOW their vent. If there is only a 1 finger gap between them, the bird is not laying. 2-3 fingers and the bird is laying. (of course it's not a precise measurement as everyone's fingers are different sizes)
You can put your fingers between their pelvic bones BELOW their vent. If there is only a 1 finger gap between them, the bird is not laying. 2-3 fingers and the bird is laying. (of course it's not a precise measurement as everyone's fingers are different sizes)