Leaders are supposed to lead. They set the tone for how their organization is to be run. They establish their expectations of what their organizations' moral and ethical standards should be and expect everyone to follow them.
Have you ever heard out of Hastert's mouth "this is the way it's going to be and we will tolerate no less," or words to that effect? Have you heard him make any bold statements against ethical breaches, self-serving pork, or any of the other crap that has taken root under GOP control -- at least any the media has latched on to? Yeah, he's supposedly "taking responsibility" for the Foley lapse, but what the heck does that really mean? Calling for an investigation? Big step! And as far as Hastert condemning it...gee, that's really stepping out bravely when one of your soldiers has been hitting on teenagers.
Sure, Hastert is probably personally ethical (as much as anybody who has to compromise with Democrats on laws is capable of doing)...nice guy...former wrestling coach...but does training grapplers make you qualified for one of the three or four most important leadership posts in the country?