Scrabble rules say thay after at least six consecutive scoreless turns the game ends.
Under North American tournament rules, the game ends when... at least six successive scoreless turns have occurred...
It is also pretty clear for me that in absolute majority of cases a scoreless turn arises from either: 1) passing; 2) exchanging tiles; 3) losing a challenge.
But can a normal turn be scoreless? Imagine that a player laid something on the board, so he/she definitely played but scored nothing. Maybe it's extremely rare, but it is a possible event, isn't it?