One of the things that happens when you are a barbershop judge is that you get to hear multiple performances of the same arrangement. (You get it as an audience member too, but you get it more as a judge as you can’t pop out for a beer and a sandwich during the early afternoon session.) And sometimes you notice over repeated hearings that certain arrangements seem consistently to elicit sub-optimal performances.
These are arrangements that, on the face of it look fine. If there were obvious technical or artistic flaws with them, they wouldn’t get picked up by lots of groups. So it takes quite a few hearings to notice that whenever ensembles sing them, they always perform better in the other song – they’re more synchronised, better in tune and more naturally expressive. I’m not going to name specific arrangements, as I don’t think that would be polite. Rather I’ll just invite you to compile your own lists from your own listening experiences.