Possible Clues:

• 'Jeopardy!' contestant, at times
• Hangman player, e.g
• One taking a shot
• “Wheel of Fortune” contestant, say
• Participant in hangman or charades
• Charades participant, e.g
• "Is it bigger than a breadbox?" asker
• 'Is it bigger than a breadbox?' asker
• Estimator
• One with insufficient grounds to express an opinion