Lurker: Practically speaking, competent assigners are aware of any (real or perceived) conflict of interest an official may have, and therefore don't compromise an official by putting him or her on a "conflict" game. In the real world, officials should tell the assigner of any conflict beforehand.
To my way of thinking, not "liking" a particular coach or set of parents is not an acceptable conflict. Admitting as much calls into question one's ability to officiate ANY game; not just those in question.
There are legitimate reasons to blackball an official. In nearly 20 years at various high schools I supported ONE blackball -- when it became apparent to me that a specific individual was openly cheering for a team whose games he periodically officiated. Found out he had a personal relationship with that team's coach.
I also suggested that the official in question not work ANY games involving teams in his GF's conference, because he could impact outcomes of OTHER games that would affect league standings, state seedings, etc. And the assigner quietly accepted that suggestion.
I'd also point out that there's a big difference between coaching and officiating. A coach is SUPPOSED to have, and manifest, a vested interest in his/her team. And parents/fans are just that. An official is SUPPOSED to be unbiased. Officials should EXPECT reasonable bias, emotion and heat from coaches and fans. Coaches should EXPECT a fair shake from officials.
