Maybe makes em thirsty. They go back for a source of water. Or they fill up eating the salt and don't need to look for more food. I know that gunpowder does something similar for cats. No not shooting them, but a line of gunpowder, or more specifically the sulfur acts as a deterrent.
What the fuck does Todd Howard have to do with this? If you are a scientist, test them on lab rats or something. You guys have those, right?
... What if all of the rats are already inside so there's no need to come in ...Or maybe they found a backdoor
Just normal cooking salt. Don't know if that's different from table salt, but basically the same one in Ai-chan's kitchen. Because Todd Howard said, Now, that guy was a rat.
You could always separate sodium from salt and have your own pyrotechnics near a source of water, I guess.