I've made ghee with salted butter...no big deal...unsalted has a shorter shelf life than salted...but it still tastes good. Unsalted tastes a little better tho (more authentic I think ). If made properly, you don't need to refridgerate it either.
This is what an article on ghee says:
"I can only find salted butter. You can still make delicious ghee with salted butter. And no, it won’t be salty.
The butter will froth a bit more during the steps in the instructions where I would indicate it should bubble. Make your ghee in a slightly larger pot to prevent the froth from overflowing, and give it a stir when it does froth up to bring it down in volume. If you’re worried about overflow, you can also just take it off the heat for a moment and stir and things will calm down. The resulting ghee will taste fabulous but have a slightly gritty texture. Also, those milk solids, don’t eat ‘em. That’s where all the salt will go! Pour those puppies down the drain. "http://blog.asmartmouth.com/2008/10/10/ ... -you-dare/
Here's some more good tips:http://paleohacks.com/questions/20369/s ... z1d9z1KmKc
I guess unsalted is used because it's from the freshest cream (as it's unsalted/unpreserved)
Whereas is it's salted (preserved) it isn't the freshest cream.
Personally , I think UNsalted tastes fresher & more authentic.