The following is a cut-and-paste portion of a Newsweek article on the Married Male Mind - and one of the best reasons to get a housekeeper if you don't already have one!

Does that mean men should give their wives a full housecleaning for Valentine's Day?
Yes! It wasn't till I did this book that I recognized that it's not just the doing of the housework that's a burden to women, it's the worrying about the housecleaning that is a burden. Finally I agreed to hire someone to help clean our house, and it had a direct effect on our sex life.

http://www.msnbc.msn.com/id/11348283/site/newsweek/