So pointing out (the rather obvious fact that) the western Christians were more motivated by misguided piety than by simple greed amounts to "defending their behavior?" Really?
First off I have two books by Madden. My views on the Crusades primarily comes from his book, "A Concise History of the Crusades."
Painting a picture where....
1. The Pope gets a plea from the Eastern Christians for help and feels it is his duty to send troops asks the Franks to take up arms against them.
2. The Franks that have been warring for years for political and financial gain, regularly defying the Church in the process, give up all worldly possessions to go help the Christians being attacked in the East.
3. Looting happens but they were there to save their souls.
Sorry but that is painting way way too nice of a picture on the Catholics.