I worked with Mike Bria at a prior employer and he's a really smart guy that quickly switched from agile skeptic to agile champion (he says shepherd) when we went through the transition from waterfall. He recently wrote a great article on infoq about how agility means truthfulness.
Everyone read that book as a kid. The emperor is convinced and the townsfolk have a good laugh. How many projects have you been on where the project manager spends his time fudging the numbers so that you can all keep your miserable project afloat for another few weeks? You know the axe will come, but you've bought more time. Is that how we like to work?
Back to Mike's point, agility is about transparency and truthfulness. I love information radiators. Take key points of data (a burn-down chart or cards-on-the-wall for example) and put it in a really visible place. Allow people to see what is important at the moment. Let people see the progress being made, or the things that aren't moving. Allow debates and discussions to happen.
Before you know it, you aren't spending time fudging numbers... you are spending time seeing the trends and correcting. You aren't hiding the failures, you are managing towards success.
If you work in a company where this is the culture everywhere, then you can kill a failing project even quicker (because it is obvious) so that you can get moved onto a project that is successful and much more fun to work on.
Agile can be about being honest with ourselves about where we are heading and what we need to do to be successful. Don't get caught without any clothes on!