snake oil
From Longman Dictionary of Contemporary Englishsnake oilˈsnake oil noun [uncountable] especially American English informal 1 something that is claimed to be a solution to a problem, but is not effective2 → snake oil salesman/peddlerExamples from the Corpussnake oil• For all his odd and scary views, Buchanan has played the fear card like a snake oil salesman hawking eternal life.• Perhaps, when the shouting from snake oil salesmen subsides, our leaders will find a way to forge a bipartisan solution.