I used to be peripherally involved in polling (not political). Our "experts" at times would throw in a "gimme question", something very obvious like "Would you rather be paid $50 or $5 for completing this poll?" We'd consistently see 5-10% vote $5.
A lot of people don't listen to the question, or hear the question correctly, or respond randomly, it's near 10% in every poll taken I surmise.