Generally, any good quality contest with a Box Stock or Out of Box category will require that the builder provide and display a copy of the instructions with his/her entry. The judges can then review the instructions to see exactly what was or was not supplied in the kit. It usually resolves any questions or issues, and that's precisely why it's done.
If the entrant fails to provide and display the instructions, the model is disqualified.
One thing to keep in mind, at least from my judging perspective: Just because the model is displayed and/or entered, does not mean it has been judged and considered for award/s. Again drawing on experience, where models have been entered in 'Box Stock' class but did not meet the criteria of the class, they were disqualified and not judged. Spectators and entrants would not have seen any indication of that, because the models remained on the table ... they just did not "win."
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