I'm not sure if this is the same point that Zaxo was making, but the test suites of other modules are only part of the picture. The other part of the picture is your test suite. A module you're using may have a terrible, non-functional test suite with very low coverage. That doesn't matter as much, though, as long as your own tests cover the things that matter to your program.
Maybe this doesn't apply to quick scripts written directly against the CPAN modules in question. But any time I'm doing a project of any reasonable amount of complexity, I tend to write most of the code in application-specific modules. This is where I do my testing, and this is where I can ensure my application is returning sane results. If a CPAN module I'm using from within this code is doing something strange, I will tend to find out about it.
