As long as you are up front with the people you are interviewing with, I don't see any harm. There's the rub though; who will want to waste their time to interview you if you have no intention of joining their company?

If you want more money you can talk to your manager but other then that, you just need to get another job. It sucks but that is reality.

The raise-by-counter-offer strategy rarely pays off. You may get your raise but only until they can find someone to replace you.