1) Doubters 2) Habitual doubters 3) People not too sure 4) People with questions 5) Show me types 6) Show-me men 7) Show-me types 1) Doubters 2) Naysayers 3) Scoffers 
skeptics, sceptics 1. People who habitually have doubts about accepted beliefs. 2. Those who question the validity or authenticity of something purporting to be factual. 2. People who maintain a doubting attitude, as toward values, plans, statements, or the character of others. Etymologically related...