Well, that is because whoever or whatever that was in that room prior to you had left thier vibes behind. Most of us do not see energy, but wether we know it or not, we feel it every day. Magic is taking that energy and working with or manipulating it in order to gain the results desired. Now as most of you know, there is white as well as black magic. I do not nor do I recommend practicing black magic.
Black magic is dangerous, selfish and uncalled for.
Most times it is done out of depiration, but, we are all human, we all have our hurts, and things don't always turn out the way we would have liked them to. Nobody is perfict, but we should all do our best to try and do onto others as you would have done onto you. And remember, that any harm that is done onto others, comes back three fold.