Flattery specifically geared towards the negotiation performance may be an at-table tactic, but it can yield great strategic benefit for serial negotiations. Statistically, it increases the likelihood of a closing in a future negotiation. This emphasizes the importance of closing important negotiations, and ensuring you know all the tactics and how to handle them professionally. Although this tactic creates a sense of camaraderie, do not let your guard down.
There is no stealth in this tactic. Someone may say, “It is refreshing to negotiate with a true professional,” or sincerely state, “That tactic you used was brilliant, it worked on me.”
The way to handle this is to disregard it. Be pleasant and gracious, but do not think you are special. Again, look at what you or your employers need and pay no attention to flattery as it can turn one into jelly.