There are things you can do to keep cops from smelling it, but the dogs are a bit more difficult to hide from. About the only way to hide from a dog is to cover the smell with another smell, like coffee.
That's not true. Dogs smell the particles that escape the material it is in. Lets say you have drugs wrapped in many layers of plastic wrap, inside sealed pvc piping, in a gas tank, heading across the border. The weed has been sitting in place for about 8 hours or so, the drug dog comes and smells, gasoline, pvc, plastic wrap, and guess what? Weed! The only way to beat a drug dog is to have the drugs packaged very well off location, then move the product within a hour or two before the smell starts to escape... Everyone knows about people trying to trick the dogs with coffee, powdered soap, hot pepper, etc and it don't work...