Conservative culture minister Ed Vaizey's encounter with BBC Daily Politics presenter Andrew Neil on Wednesday was a classic of the genre.
The pro-EU MP struggled to explain the figures behind the Treasury's claim that Brexit would cost each UK household £4,300 by 2030. And Neil pounced.
The figure is based on a prediction that the UK's GDP would shrink by 6% if it left the EU.
However critics of the analysis, including the BBC's 'Reality Check' website, have said the government is confusing GDP per household with household income.
Neil said George Osborne and Vaizey were guilty of using a "dubious metric" to make the pro-EU case.
"You’re not measuring household income in this equation, you are measuring GDP per household. If you wanted to measure whether households would be worse off or better off, you should use average household income and you didn’t, why not?" Neil asked.
Vaizey told Neil: "Well we live in a free country. So you can dismiss that document".
As Vaizey appeared to try and dodge a question, Neil told him: "I’m not going to let you talk your way out of something."
The minister replied: "I’m going to try."
Neil hit back: "Well, you’re not going to succeed."
The BBC interviewer also grilled Vaizey as to why the Treasury prediction of the average loss to each household by 2030 was based on the number of households there are now, rather than the number there would be in 14-years time.
Neil asked: "You use the number of households now, 27 million, but to get to the GDP for 2030 you assume a huge rise in immigration which must mean there will be a lot more households. Why do you do that?"
Neil pointed out the Treasury based its assumptions on future immigration figures that would be higher than the government's 100,000 target. "Why do you assume you’ll break your immigration target?" he asked.
Vaizey said the £4,300 figure was being talked about by the chancellor as it "brings alive a figure as to what it mean" if the UK left the EU. "The growth of the UK economy would be lower if we left the EU," he said.