Think of it more as being a pattern interrupt. They are saying no to you over and over, so by asking the question, "So you have perfect user retention then?" they can either say "No" instinctively which opens your sales pitch because they've now told you they have a user retention problem, or they stop and think about the question in which case you've successfully interrupted the pattern of no's that preceded the question and can further the discussion.

There are definitely better examples I could come up with, but now I'm stuck with this one because it's what I quickly typed out earlier.