when i got my ferret stinky, his glands were already taken out, ,which was suppose to eliminate some of the musk. but like you i could still smell him. so i would give him a bath all the time. come to find out giving a ferret a bath will just make his skin produce more oil, thus making him smell more. the less bath you give him or none at all unless he is really dirty makes the smell less strong. i have had stinky now for 9 years going ten and even though he gets to play outside of his cage a lot. i seldom let him play in the grass, but he does get to play on the porch on nice sunny days. I also have him on a ferret diet but would also give him raw chicken at least once a day. this he truly love and would eat it with much gusto.But most of all, in order to keep the smell in control. you really have to keep his cage spotless. I have tried using all kind of litter to just end up finding stinky rolling in it and thinking it's a sand box. But what has worked for me is shredded newspaper. he poops and pees on it and his cage has a grate so most of the pee goes to the bottom of the cage which is also lined with newspaper. but him pooping on the newspaper makes cleanup easier. i use a paper bag from the grocery has gloves and just gather the soiled newspaper and wrap it in the plastic. this i do once a day preferably in the morning. So giving him fresh news paper everday keeps it clean. plus not letting have any treat unless it's a meat base product does help. Ever since have started to give him a more natural diet his poop has never been runny or stinky. He eats ferret food as a base of his diet and chicken pieces once in the morning. Sometimes this he will tire and i would give him chicken heart or liver, but not that often. or i would not give him any chicken for a couple of days and he'll want it again.
i hope that this helps. My stinky is 9 going 10 this year and is still going strong. I have read that most ferret don't live this long and i'm glad that my stinky is still here. Read and educate yourself. And try out what you think is good for you and your ferret. All ferret are not alike. What might work for ferret A may not work at all for ferret B. But keep in mind. keeping it's cage clean (meaning setting a routine that you can easily follow) do make ferret care easier to live with plus, keeps your ferret happy as well. By the way if you buy a cage pick one that has a grate, this helps to prevent him from rolling in his own stink. :O)