The Top Ten Reasons Why Linguists Are a Pain to Play Scrabble With:

10. They think of their own native speaker intuitions as a higher authority than the dictionary.
9. They argue about whether they should be spelling phonological words, or syntactic words.
8. They know that anyone can coin a word, and so they do.
7. They try to claim a separate score for every reading of an ambiguous word.
6. They try to claim credit for spelling CV-skeleta.
5. They think it is OK to play proper names, since there is a productive zero-derivation converting them to common nouns. (Semantics: λx[x=α], for proper name α.)
4. They use boustrophedon writing to cover the scoring squares.
3. They won't let you count the extrametrical part of a word.
2. They keep trying to spell empty categories.
1. "Move α" makes it too easy to get to a triple word square.