THIS COULD BE A REALLY REALLY BAD IDEA.
salt water and electricity will 'break' the salt into Sodium and Chlorine.
Cl is a deadly gas, the remaining Sodium will likely form Caustic soda.
Edit: Yeah I looked it up, here's a video
I'd say don't salt your juice.
Okay I can say from view of the video that is what happens when you electrify salt water.
Heating up salt in water will not change the composition. IE... if you leave a pot of saltwater on the stove it will heat up and evaporate, even create steam vapor that is entirely safe to breath. And that is what our atomizers do after all. They evaporate our liquid to create our beloved vapor. They do not electrify it. So I am not convinced that adding salt would be harmful at all. These are 2 entirely different chemical reactions to two very different elements introduced. One is electricity and one is heat. We did a similar experiment in high school that turned our pennies different colors by adding electricity. You could not do the same with pennies and heated up water. So very different.