Nothing chafes my hide as much as someone texting. I've been racking my brain, trying to think of an example of when text-messaging is polite, and, in truth, unless you're by yourself, with no one around (or possibly on public transportation), then it's okay to text.
Yes, I realize it's quick. Yes, I know it takes you "just a minute."
But when you're spending time with the words on the phone, you're ignoring those around you. This is called "not being present" or "not being in the moment," or just plain "rude."
Yes, I know you are physically there. But once you take your attention away from whatever is happening before you -- to take a cell phone call, to text, to check the sports scores -- you've just taken yourself away from the people and doings in front of you.
And an important life rule to remember is that the person in front of you is always more important than the person (or sports score) on the phone. Any successful sales person knows this -- now, let's all know this. And let's live it.