On the basis of McClellan's book, it can be argued that the present administration is guilty of horrendous crimes -- crimes that could only have been committed because loyalty on the part of individuals.
McClellan as White House spokesman lacked experience, talent, charm, agility, depth. But Bush and Cheney saw these defects as an advantage. They actually wanted the executive branch to become more opaque, and he was the perfect man for the job.
The blowback from McClellan's tell-all illustrates the administration's intolerance of dissent. The lesson to take away is that no president can govern effectively if they take criticism as disloyalty.