[hunter2_]

You have a valid point, to which I'll concede. The rule book gives an example (spanning pages 4-5) where a guesser uses prior clues to select a card while the count is still within the number stated by the spymaster, but I suppose an allowance for guessers to deviate in this way does not also imply that spymasters may deviate in this way. Mea culpa!

Taking this a step further, given that it's well-known that a clue is deemed invalid when it pertains to cards in certain non-definitional ways (sounds-like, number of letters, etc.), it seems extremely reasonable to call a clue followed by N invalid if it doesn't pertain to N cards in a definitional way.