Strange Bathrooms

The building I work in is a 6-story biology building (one of the taller buildings on campus), and there are about 20 rooms per floor.  It has separate men’s and women’s bathrooms, like most buildings.  But there’s only one bathroom per floor: the odd floors have women’s bathrooms, and the even floors have men’s bathrooms.  The sinks are the kind with separate knobs for hot and cold, which isn’t odd... but on some floors they both turn the same way for "on," and on others, they turn in opposite directions for "on."  However, the sinks and knobs all look identical.