It is always a good idea to clean your rabbits scent glands every month. Scent Glands can become clogged with a wax type substance. Some rabbits produce more of a scent musk than other rabbits and when you go to clean that aren't that bad and the waxy substance has a very pungent smell.
When you go to clean you want to use Q-Tips and you might need more than one and I also us Hydrogen Peroxide. Dipped the Q-Tip in the Hydrogen Peroxide and gently clean the waxy buildup out of the scent gland.
Here are photos of where your Rabbits Scent Glands are location and a before and after photo also that I made. (Thank you Bluebell for helping lol)
(Photo 1: Where it says Anal Glands is the Scent Glands)
(Photo 2: The Before and After Photo I made of a cleaned and not cleaned)