It is part of a politician's skills to be able to deflect questions he doesn't want to answer. You will see it at Question Time in the House of Commons. It can also be seen outside the chamber when the media are seeking to get answers. I know that prospective politicians are given training (as are Press spokespersons for companies and charities) into steering an answer to ensure that the person being questioned gets THEIR point across.
But does it work?
In the short term perhaps. But in the long term such evasiveness does not go down well with voters. Similarly in exams - it will do you no good at all to write about what you want to say, when the examiner is seeking to test a particular area of subject knowledge that you don't want to discuss. Deliberate evasiveness may look clever - but it won't earn marks. Similarly walking into an exam room and telling the examiner what you've learnt, rather than answering the question set - and this can be the result of misreading a question, as much as evasion - won't be rewarded.