We should acknowledge virtues even in those whom we dislike, and do so without mentioning any of their bad traits. Many of us find this very difficult. When acknowledging a good quality of a person whom we dislike, we invariably follow it with a list of "buts," and often share a whole litany of complaints against the person.
We should make an effort to acknowledge positive traits in those whom we dislike, and force ourselves not to mention anything negative about them. After all, would we think it fair if someone acknowledged something good that we had done, but then described our weaknesses, faults, and all the things he or she did not like about us?— Joseph Telushkin in A Code of Jewish Ethics: Volume 1