Don't be too quick to judge
Working long hours is not necessarily the mark of a bad manager. Some managers work long hours by choice to escape a bad home life (or no home life). Some prefer work over anything else, as it may be the one area in their lives where they feel capable and useful. Others just plain like to work more than any other activity they could choose -- their work IS their hobby and vice versa.
In the United States, in particular, the "Protestant Work Ethic" still influences many people to equate hard work and long hours with moral virtue.
Workaholic managers I have known typically don't expect the same kind of commitment from staff or peers. As long as they're good at their jobs in other respects, putting in long hours at work is not a negative quality.
