If your dog is scooting her rump all over the floor, it really makes you reconsider walking around in bare feet. Of course, she isn't doing it to mess with you -- she's just uncomfortable. Figuring out why is relatively simple, and can help you seek the right treatment.
The most common cause of butt-scooting is your dog experiencing issues with her anal glands, and all dogs have them. These little fluid-filled glands sit near your pooch's rear exit door, and they typically expel their pungent juices regularly. They can, however, get impacted, filling up with foul-smelling fluid that irritates your dog's bum and your own olfactory senses. If your dog is scooting, this is probably why, and a nasty aroma of fish and copper is a dead giveaway.
Because the modern technological miracles of toilet paper and bidets are beyond your dog's intellectual capabilities, she can't clean her bottom that well. Most of the time, the dog's backside is self-maintaining -- notice how clean it typically stays even after she goes to the bathroom. Sometimes, though, her waste can get caught in her fur and dry up, which is as uncomfortable as it is gross. She doesn't like it any more than you, though, so she's going to scoot across the floor to try to get it out. If you notice that your dog has dried waste hitching a ride in her fur, do her and your carpeting a favor and brush it out.
Despite popular belief, dogs scooting on the floor aren't doing so because they have worms -- most of the time. Unfortunately, a tapeworm infestation can irritate her bottom, particularly when she's expelling them. Tapeworms are visible in your dog's waste, so if she's developed a scooting habit, keep an eye on what she's making -- it could have an unpleasant surprise inside.
If your pooch has anal gland issues or tapeworms, she needs professional help, period. Veterinarians and even some groomers can give an anally-impacted dog a gentle massage that expels any nasty buildup in her anal glands -- and if you ask, they'll give you professional instruction on how to do it right at home in the future. As for worms, your dog needs a professional evaluation of the severity of her infestation, for which your doggie doc will prescribe a course of medicinal treatment.