I think this "clean house when you go out" thing is a lot like the "clean underwear" thing. My mother always said that she wanted her house to be clean when she went out in case she got in an accident and someone had to come to her house and get her things because she was in the hospital!!
Not unlike the wear clean underwear incase you get hurt and taken to the hospital mentality!!
Even if I'm gone for a few days, I clean my apartment. I don't know why, because my neighbor, who takes care of Ivo, has seen my place when it was a wreck. I guess I do it because I like to come and not have to worry about cleaning for a few days. The last thing I want to do when I come home is wade through dust bunnies!