Hi Sugar Mama, Zombie is right you can use salted in a pinch. But unsalted is what you should strive for. It is usually understood in recipes that for baking you use large eggs and unsalted butter. Salt content varies by brand and it would be nearly impossible to balance extra perceived saltiness without compromising the texture of the frosting. Unsalted butter also tends to be fresher as salt is a preservative. Enjoy your buttercream!

Unless you're going for a salted caramel taste, I'd get unsalted butter for all your baking.

I always use salted butter in everything I make and I make around 15 cakes a week..all delicious with no complaints! Salt brings out the flavour of all foods after all

I prefer unsalted myself because the amount of salt in regular butter doesn't seem to be too consistent. That being said, if I don't have any at home, I use regular and it still tastes great!

The gold standard for buttercream is one made with unsalted butter. I agree with ChefJune that using salted butter definitely affects the taste.

Definitely unsalted.

From experience, I'd say Salted Butter is best to use because the recipe for making frosting calls for salt. So why not use salted butter? What if you ran out of salt and never noticed at the time you go to make your frosting, you won't be able to add it. On the other hand, if you already have "salted" butter, then there's no need to add it because it'll already be there. The role that salt plays in frosting is it provides balance to the taste. Most people want something that's sweet but not too sweet. I believe that a good balance in taste is best.

It's not going to make a significant difference in your frosting. I always use salted because icing contains so much sugar, it helps to balance the sweetness.