The biggest deterrent to ferret ownership is their musky smell. Mom's in particular seem to be most negatively affected. If they smelled (or didn't smell actually) like cats they could be considered one of the best pets: small, smart, comical, trainable.
Ferrets have anal scent sacs that are used to mark territory in wild ferrets. However, most ferret breeders remove these glands in both male and female baby ferrets before they are sent to market. The biggest contributor to ferret smell are the musk glands in the skin, concentrated around the face and over the rest of the body. They remain intact. They are primarily activated by sex hormones. Therefore, the BEST odor prevention is to spay or neuter your ferret! (not to mention the health benefits that spaying will have for your female ferret)
Over-bathing strips your ferret's skin of natural oils needed to keep it supple and strong. If his skin dries out, it will stimulate his musk glands to overproduce to compensate for the lack of oils - exacerbating the ferret smell issue. Bathe only once a month or so and use a ferret-only, high-quality shampoo. It may cost a little more, but it is researched and developed to replenish the oils to keep the skin from over-producing the objectionable oils.
Dirty Ears can cause ferret odor problems. Ferrets get waxy build up in the ears just like other animals, only maybe a little more frequently owing to the high gland secretions. They can also get ear mites - particularly if they go outside frequently or live with dogs or cats who do. Check his ears periodically and clean with a ferret ear cleaner solution.
Ferrets that are fed on low or no-grain diets will normally eat less and receive more nutritional value than ferrets fed low quality high-grain diets. That actually makes higher quality ferret food more economical to say nothing of the clean-up. Ferrets fed high quality diets will excrete less with less odor, making clean up much easier. (You will notice the stools will be smaller, dryer, darker, and less smelly)
Ferrets fed low quality fats such as beef tallow will also have stronger fat excretions in the skin, heightening their body odor. Beef tallow also makes their eliminations more stinky. Ditto fish oils. Try different foods to find one that suits your olfactory senses better.
His litter box must be scooped of fecal matter twice a day if possible and changed completely each week (Including washing the pan) Mom will not abide a dirty litter box. The best litter we have found is re-cycled newspaper or alfalfa pellets. The former is just great all around. The latter actually has a great clean scent of its own.
Some products will help by working from the inside out to help control litter box odor. A daily additive to his water bowl may help to neutralize odors before they make their way out in the stool. However, they are not a substitute for cleaning the box.
Because he rubs his skin and hair against all of his cage accessories, it is important to wash them frequently (about once a week or so). His hammocks and bedding may wear out a little sooner, but your whole house will smell better. Keep an extra set of hammocks and toys to change out as you wash. He will love the variety anyway.