I'll never forget my first year in college.  I return home for thanksgiving and of course I bring mom my laundry.  She takes one look at my sheets and says: "yuck, when was the last time you washed these things?"  I reply, "I haven't washed them at all!"  I than ask her how often she washed my sheets at home and she tells me: weekly.  I was utterly shocked.  I had NO IDEA that sheets were washed that often.  What an idiot!!:)