I quite often write characters with class differences in the modern day (e.g. Ginny/Pansy from Harry Potter, or Gwen/Morgana contemporary AUs), but I get uncomfortable at the point where class segues into authority figure/person authority is exercised over. For me, lady/maid pairings are always close to dubcon territory, because the servant is so vulnerable to being fired, accused of theft etc. and can be literally ruined by their employer if they turn down an advance or displease them. Sometimes lady/maid can be very sexy (Sarah Waters' Fingersmith is a great example) but I think it requires careful handling.

Mind you, if someone was really into dubcon and authority figures then I could see this scenario being great!