A clean bicycle will be a well tuned bicycle and will serve you much better than a greasy, grimy bike that you rarely have time to wash. Everything on your bike is open and easily attacked by dirt and grime and if you do not regularly clean it off, you risk not only losing performance, but endangering yourself with shoddily performing parts.
Often when or if you buy a new bike it will always come with a stock seat. The seat that is stock on the bike is made to fit and take your weight. Most of the stock seats are very uncomfortable and hurt. That is why you can get other bike seats with a gel mesh that is like a bed for your butt while riding your bike. If you have never ridden with a different bike seat then the one that is stock on your bike then you're in for a surprise.