>"what does THINK_TANK believe will happen to the economy under Trumps tax plan" (as opposed to "what is likely to happen under Trumps tax plan", so there would be no political disagreements)

You're giving people too much credit. When showed the controversial comparison photos of Obama's and Trump's inauguration crowds and asked which photo depicted a larger crowd, some Trump supporters indicated the Trump inauguration simply because they recognized the controversy and refused to give any credence to the perceived insult, even going so far as to give an obviously false answer on an ostensibly objective poll.