When does a breakdown become a “messy” or “unplayable” ruck?

A breakdown becomes a “messy” or “unplayable” ruck when the ball is obscured or trapped, making it impossible for players to contest possession legally. This often occurs due to players not releasing the ball, collapsing the ruck, or other infringements that impede fair competition. When the ruck becomes unplayable, the referee may stop play and award a scrum to restart the game.