If you’re like 75% of smartphone users, you bring your lil’ pocket computer with you into the bathroom. And you probably touch it with your greasy fingers mid-meal all the time, too. And of course you take it on subway, and to the airport, and the movie theater, and to endless other public places where other germy disgusting human beings are present.
Basically, your iPhone is a bio-hazardous mess. There are plenty of wrong ways to clean it, and there are some fancy shmancy sanitizers you can buy -- but even for something as simple as wiping off smudges, there are dos and don'ts you should follow. Protect your investment, people! (Er, at least until you upgrade.)