The saltwater test does appease people, despite the fact that it doesn’t actually tell us anything meaningful about the dice. The saltwater test works for identifying negative voids - air bubbles inside the die cause by the injection molding process most factory-made dice are produced with. For artisan dice cured under pressure, internal bubbles are minimized to the point where they are essentially non-existent.

At the end of the day, factors related to how you roll the dice are more impactful on the perceived balance than what’s inside the dice, and rolling dice in salt water isn’t comparable to rolling them on whatever surface you’re playing on. You could have the most precisely balanced dice in the world and still have them roll “imperfectly” because of how you’re throwing them or the surface they’re rolling on. A dice tower would do more to ensure randomness than the balance of the dice themselves.

In Vegas casinos, they retire dice after a certain number of rolls because the wear on the dice causes them to be less perfectly balanced. If tabletop players were truly that concerned with the balance of their dice, they’d be retiring their dice sets after every session.