As well as the usual "what they said" to joshin and user246, I'd add this: there's no guarantee that the number of times a bug gets reopened is going to give you any useful information. Here's a few reasons why:
- There are several different bugs involved, but they all have the same symptoms. Here, someone could have reopened the bug thinking it was the same problem, but it was a different problem with the same symptoms. You have no way of knowing whether the reactivation of the bug report is one of these or not.
- Someone creates a new bug report for the same problem, and it isn't detected as a duplicate. This is particularly common with large, complex systems where the manifestation of a problem can differ depending on the user's configuration, or where everyone reports problems to the same system.
- The bug report is activated in order to back-integrate the fix into another version of the application.
Basically, in anything that's got enough complexity to generate... interesting bugs, human differences will make bug report tracking an exercise in false alarms. Probably the most specific you're likely to ever get is which areas of the system generate the most problems, and that's one you don't need a bug tracker for - every tester who's working with a system quickly gets a feel for the trouble areas.
In addition, as joshin pointed out, there's the risk of perverse incentives. Companies where developers are penalized for introducing bugs often develop a completely informal system of bug reporting so that testers don't feel they're harming the programmers by reporting problems. A bug that gets reopened a lot may not be one that's incorrectly fixed or where the problem is misunderstood. It may be an intermittent problem where round 1 involves adding logging to try to trace the problem when it occurs, round 2 adds more logging based on the information derived from round 1, round 3 includes a possible fix but since the problem can't be reproduced by the team, there's still more logging in case the fix isn't right, and so forth.