If your vacuum cleaner smells, most of the smell is created by your vacuum cleaner bag. If your vacuum cleaner has an outside bag then remove it and give it a wash in your washer with some lemon juice. Then dry it outside. It will freshen it up a treat.
You can stop your vacuum smelling by sprinkling baking soda over your carpet and vacuuming it up. It will remove odors from your carpet and your hoover.
For a fresh smelling vacuum, put 2 tablespoons of powder laundry detergent (scented) directly in vacuum bag. Lasts for about 10-15 vacuums!
Adding a bag of your favorite potpourri and setting it inisde your vacuum, you are going to give off great smells that you like most when your are running the vacuum.