gull•ible alsogull•able \ˈgə-lə-bəl\ adj
1818 : easily duped or cheated --gull•ibil•i•ty \ˌgə-lə-ˈbi-lə-tē\ n --gull•ibly \ˈgə-lə-blē\ adv - Merriam-Webster, I. (2003). Merriam-Webster’s collegiate dictionary. Includes index. (Eleventh ed.). Springfield, Mass.: Merriam-Webster, Inc.
I don’t endorse negative thinking.
I do, however, support critical thinking. Critical thinking involves enough negativity to say – “prove it,” “I don’t understand,” or “that doesn’t make sense.”
When it comes to financial matters, too many people want to believe something is true so they stop thinking critically. Instead, it is important you verify financial advice.