The problem with concepts like selfishness and selflessness is that their main constituent, the self, is not properly defined. I think this is why the works of Ayn Rand are sometimes misunderstood—people project their own definition of self on Rand’s selfishness, and so get a version unintended by the author.
There’s one sort of self that when turned to selfishness can become a sort of selfless selfishness. I think a more accurate term for it would be creative selfishness—though again, using such terms leads to a very distorted picture. Instead of using your character, your possessions or your status to define yourself, this sort of self uses in that place its work, its products, its art. The artist is not the work, but the work defines the artist. The artist focuses his energies on his work not to please others, or merely gain wealth, but for the sake of that work—the work itself is the goal. He is selfish in that he focuses on what he considers to be the self, yet he is selfless in that this self lies not internally but externally and that he doesn’t simply take—power, money, status—but creates and adds to the world. Of course everything is linked, and if the artist produces great work, things like money and status will follow, but they are not the main focus of his work.
The concepts of selfishness and selflessness alone are neither good nor bad—the terms themselves are too vague for this evaluation. I think it’s more important to focus on creation versus destruction and place the terms in that context. Is it creative selfishness or destructive selfishness? Is it creative selflessness or destructive selflessness?