You need a few material before you get started.
1. An odor of marijuana.
2. A vacuum
3. Carpet Fresh or Febreze
Spray Carpet Fresh or Febreze on your carpet/floor. Once you have sprayed a good amount of the floor, vacuum the area that you sprayed with your carpet fresh. This will fling dust and carpet fresh into the air resulting in a mish mosh of interesting odors in the air depending on whats on your ground and inside your vacuum. It will definitely change the scent of your room and can save you a lot of hassle with hostile authority figures.
PLUS, your room will be clean. There is no better deal than that. I understand you can spray all of this stuff in the air to begin with, but this method gives off a less suspicious smell than tremendous amount of berry flavored spray and provides some air circulation.
The Weed Street Journal