Against strong defence - kingside attacks when castled kingside can be countered but can also result in spectacular play. Look at some of the Fischer games or even Fritz's game with Kramnik for ideas.
Attacks with sameside castling often happen when one player allows the other to get too much development on the side his king is on, or allows him to get a strong center and/or space advantage on the side of the opponents king. There is a whole section on this in the book The King in Jeopardy by alburt and palatnik