Mirroring is a vital aspect of sales. It is important to match the tone and mood of the prospect to make them comfortable and happy. Many salesmen forget this aspect and proceed at their own pace, without a care in the world. One fictional instance in which this happens in in the movie Love Actually. The prospect is clearly in a hurry, but the salesman proceeds to move at his own slow and steady pace. Have a look.
As you can see, the whole exchange is absolutely bizarre and he ultimately lost the sale. It is of the utmost importance to stay at the same pace as your client and to never let your own desires get in the way of the sale. A more concrete example, may include simply speaking too fast to a calm prospect, or not giving someone who loves affirmation any affirmation. The key is to pick up on what the prospect wants and expects and deliver on that.
Holy Cow! That scene is so so so so so so so funny, I feel for the customer every time. Yes; mirroring is important in any communication. The more mirrored you are (and without forced mirroring) the more fluidity the conversation will be.