Ultimately, you are sooner or later caught and at that stage it becomes very embarrassing situation to face. Thus, it is advisable to be free, frank and straight forward in response to a query or a question.
Have you completed the job instead of positively reply telling I went there, the concerned person was not available, had a problem, etc. The answer would have been first in yes or no followed by justification later.
The witnesses change their evidence very often, maybe at times under political, police pressure or money bargain - forgetting that his / her statement can turn the case on either side.
In the Best Bakery case Ms Zaheera Sheikh changed her statement number of times under certain pressure, and the Hon’ble Court very rightly sentenced her to one year imprisonment on this accord.
We must be straight forward in reply to a question. While being interviewed it is always better/ advisable to say no in case the answer is not known instead of ‘ if and buts', 'I think so’ , etc.