You will find that gliders do not offend the nose like other small pets such as hamsters or gerbils. They do have their own distinctive scents, but usually these are very faint and you won't even smell them unless you are right up next to the cage.
NOTE: If your gliders smell bad there may be a problem with their diet. If you overfeed them vitamin supplements, for example, their urine will develop a very strong odor and even daily scrubbing of their cage and all accessories won't keep it under control. Try cutting out all vitamin supplements completely; the smell should disappear within a couple of days. Then add the supplements back gradually until you determine how much you can give without making them smell bad.
Male sugar gliders have a scent gland in the middle of the top of their head, which causes the typical bald spot in the center of the wide part of the black stripe there. Another gland is located in the middle of their chest. A third gland, an anal one, is shared by males and females alike. The females also have a scent gland in their pouch.
The male's forehead and chest glands are used in marking his territory and his mates with his scent. Gliders produce at least three distinct odors. One is a sweet, flowery smell; another I don't know how to describe, but it is not really offensive. It can get relatively strong at times, when they are breeding, but after a few days it dies away again. The third is a pungent smell that is produced by the anal gland when a glider is afraid.
Gliders use urine to mark their territory, so you will need to clean their cages and furnishings periodically. Otherwise though, they are very clean little animals. See the housing section for more on the topic of cages.