Think about it, what's the most common tactic when people disagree with someone politically? Personal attacks using buzzwords few people can actually properly define but have now all but lost meaning.
Words like "fascist" and "Marxist", once used to describe specific political ideologies, are now just buzzword used in desperate attempts at character assassination.
Probably wouldn't be fool-proof, many politicians are too careful with their words and may decline to give a direct answer to some of them. If someone like Trump, someone prone to flattery and routinely speak before he thinks, were given a friendly environment for an interview to put his mind at ease with these questions casually thrown in, we could then accurately and definitively place said politician on the political compass using answers that equate to at least the next best thing to straight from the horses mouth. For all others, maybe we could cross reference interviews to see if they answer in interview x what they declined to in interview y.