Everybody knows that it is the nature of sales to experience fluctuating results due to all sorts of factors beyond one's control, such as seasonal issues, economic or market drifts, or changes with a product formula. The interviewer is looking for a degree of sales consistency, but also is interested in how you have faced problems and acted to improve your performance where necessary.

If you simply answer, "No" to this question in your interview, it is not likely to gain favour or be convincing, and it is better to show that you understand that a period of low sales can occur and is a challenge to accept and deal with. In your answer show the interviewer that you have the ability to constantly learn from experience and are ready to change tactics to overcome difficult challenges.