CSS Performance and Maintainability
Specificity wars, duplication and stale rules all result in CSS bloat, an issue which I have found to be common when working on large projects. This is an issue which has a huge impact on CSS performance, not only in terms of load time but also in terms of the additional effort involved in maintaining the code base.
The principles laid out in SMACSS and OOCSS can go a long way to combating this and restoring order to unmaintainable CSS. If you have noticed this phenomenon in the projects you work on then these presentations from Nicole Sullivan are a great place to start.