gullible
adjective uk/ˈɡʌl.ə.bəl/ us/ˈɡʌl.ə.bəl/
容易上当的，易受欺骗的，轻信的
easily deceived or tricked, and too willing to believe everything that other people say
There are any number of miracle cures on the market for people gullible enough to buy them. 市场上有好多种所谓的奇效药，专门诱骗那些轻信的人掏腰包。