True swim bladder is not something that you can easily treat.
Let's get back to basics. A swim bladder is nothing more than a pocket in the digestive tract where some air or gas can build up. That helps the fish stay upright and if it is the right size it keeps the fish from sinking to the bottom. So what can go wrong? The swim bladder can fail to develop enough and the fish will tend to sink to the bottom and have to move in order to stay off the bottom. Some fish have no swim bladder and this is their normal condition. An example is the group called darters. If they are not darting around, they are laying on the bottom. The other thing that can happen is that a fish eats too much and it swells its digestive tract more than it should or gets some swelling in a part of the path where it should not happen. That can end up with the fish unable to sink in the tank or even, if the air pocket is misplaced, can make it swim sideways or upside down.
In a mild case it is possible to deflate the air sac by using a sharp hypodermic to remove some of the gas and let the fish right itself. The technique should only be tried after getting adequate instruction on techniques from a veterinarian. Another possible cure for an extreme case would be a surgical reduction to allow the fish to swim upright. This was demonstrated at a club meeting by a vet in our club who brought in all of the needed equipment and some help to anesthetize a known sick goldfish which could only swim at the water surface upside down. After the surgery the fish's quality of life was improved because it became a belly slider instead of swimming upside down. It could even get where it wanted to go in the tank as long as it kept swimming. As always, with a swim bladder too small it would sink when it stopped actively swimming.
I have no idea what people are seeing that they think they can treat with salt or similar remedies but it is not truly a swim bladder problem.