Well i smoke in my room everyday, and live wit my parents, and they hardly ever know if i toked...
I have a scented oil plugin in my wall, and it keeps my room smelling great, and after i have a sess, if i smell chron, i spray "fabreeze air effects" They come in a shitload of different scents, and they are GREAT for covering up the smell...
Heres a picture of them..