I religiously tip housekeeping staff because they are the "unseen heroes" of a pleasant stay. It bugs me that people like bellmen and valets (typically male) get the Benjamins for 5 minutes work and many people completely disregard the housekeepers who spend a half hour cleaning disgusting crap out of your bathroom and do back-breaking work to give you 8 hours of sleep in a clean bed. So I DO value the service that housekeepers give me.