Is friendly class or function a bed design?

Question

Usually if we use dynamic_cast, it is mean that our design is poor. If we use a friend class it's a poor design because it's a lack of functionality in our class? Or maybe the same as in operator overloading it have to be a friend class if we want declare them out of the class. What do you thing?

Answer 1

I think that friend classes help to encapsulate functionality linked to a class which are not directly linked to an instance of the class (such as operator<<).
But I am not sure either :/