I had a bug with the geek trait a couple of weeks ago. One sim in my household had the geek trait and would get tense every two hours for not playing games. I guess he also infected his roommate who has never had the trait at all but she also got tense just like a sim with the geek trait would, although, again every(!) two sim hours. So they could play a game and a little while after get tense. I mean we all love games but come on. I deleted the save and added them to another save and it stopped (for now).
It's annoying when a sim who have gotten different traits acts according to their old traits but I usually just resort to, like some others in the thread have suggested - clone them in CAS by making a twin and then deleting the original. It's time consuming if you want the same outfit etc. but it does the job.