I have heard that outstanding recommendations don't help that much, because each person selects their own recommenders and you would expect most of the qualified applicants at top schools to have top notch recommendations. If everyone's got great recommendations, then they can't do much to distinguish you.
On the other hand, a lukewarm recommendation can kill you. It raises questions about your judgment, and obviously why in the course of your life, you can't find 2 people to say nice things about you.
I do think that schools understand some recommenders are unwilling to take the time to do a decent job, while others don't understand what schools are looking for.