At home when I'm smoking indoors I usually like 5-10 minutes before I'm going to smoke inside my room I'll light an incent and then i'll smoke close to my window, obviously blowing the smoke out the window and cashing the bowl outside the window, then I'll light another incent when I'm done and the room has never smelt like weed.

When I was at college these past few months and living in the dorms I would basically put a fan facing outside the dorm window and light up and blow the smoke through a doob tube outside the window and then just spray febreeze type stuff throughout the room. Never smelt either.

As long as you're smart about it, it's very hard to get caught, just use common sense.