This article does a good job describing the smell of Marijuana and even details how they differ depending on the state of the plant/product.

To summarize:

As a growing plant, upon harvest, and when dried Marijuana plant smells “slightly weedy, piney “skunk” scent that gets stronger as the plant grows older. When cannabis flowers and blooms, the scent becomes powerful.”

At the point of purchase they can smell “earthy, herbal, and woody. Sometimes the plant scent carries notes of lemon, apple, diesel, or plum. Also, “Dried marijuana smells a lot stronger than some other dried plants.”

When you’re smoking marijuana, the natural scent of the cannabis scent is amplified by the smoke it creates. Fire, smoke itself, ash, and the smell of rolling paper add additional layers to the scent.

When a person is smoking cannabis, “notes of lemongrass, pine, fire, and wood may stand out. The distinct “skunk” smell of marijuana is often reported.”

The article also says that the person who smoked weed has a ““skunk” odor mixes with the scent of fire and smoke, and can also layer (and amplify) the smells of sweat and natural odors people naturally produce. Some people say the after-smoking scent can take on notes of mustiness or a faintly foul, overly sweet scent.” And that the smell of marijuana smoke can cling to a person’s hair, skin, and clothing.

Hope this helped you.