A special licence is needed for the likes of Hooters and "adult" places, the licence will state the size of premises and the number of staff etc, so they then can advertise a particular gender. All female gyms etc can do the same, I think that it is right that this is still allowed for jobs that don't involve personal care. The clever way of getting round a particular culture, is to ask for "Polish speaking" etc and then just hire the actual Polish, applicant.