I have a Superboy story from the early eighties where Superboy goes into the earth 2 universe and trains a young Kal-L in the use of his powers. While this looks cool to the Superboy audience, it hurts the credibility of the earth 2 Superman in a way because it makes it look like it wasn't really his decision to become his worlds premier hero.
There are a lot of Superboy stories from the 70s and 80s that just buried any respect I had for how the character was handled, sadly, because I really loved 1950s Superboy in particular.