Because they’re everywhere else, so why not here, too? Having friends come to stay is the best incentive for me to invest some time and thought into interior decorating. We were in our current apartment for a good six months before we hung our first piece of art. We had the art the whole time, propt up against the correct wall and everything, we just didn’t actually hang it until my sister announced she was coming down (one of the paintings was hers).
I read a great tip recently. If you have visitors stop by your place unannounced and you only have a couple minutes to tidy up, focus on the bathroom. It’s the only place where they’ll be alone and have time to really check out their surroundings (hopefully, uncritically). So instead of making sure your bed is made (because, they’ll probably never go into your bedroom), give the toilet a quick scrub, make sure your cosmetics are all put away, fold the towels and light a candle. I like to think, too, that with our setup now they’ll be more interested in the books on our cabinet shelf than they will be with the rust on our faucets or the rolled-up toothpaste tube I forgot to put away.