If you have no use for a card, you shouldn't apply for it. Even just to see if you are able to get it or not. We're all guilty of doing it at some point, but I just try to remind myself that the application inquiry will stay with me for TWO years. That's a long time for something you just do on a whim.
The lesson? Don't do it on a whim. Do it if you feel you will get a real benefit out of the card. And this isn't the same for everybody. Many people on here love certain cards that would be less useful to others based on their spending patterns. It's a personal thing. Don't just apply for something because you want to see if you can get it. Make sure the benefits are well, beneficial to you 