I admit that my understanding of the word's definition is heavily colored by its use here and on Overcoming Bias.

However, I will note the Wikipedia article does hint at the possible duplicity of signalling that I have implied.

The sender observes his own type while the receiver does not know the type of the sender. Based on his knowledge of his own type, the sender chooses to send a message from a set of possible messages M = {m1, m2, m3,..., mj}. The receiver observes the message but not the type of the sender.

Thus the receiver determines the probability that the signal has a credible basis. A sender sufficiently skilled at manipulation could fool the receiver into believing a false signal. More relevantly, an insufficiently skilled signaller of curiosity would be unsuccessful in overcoming a receiver's probability distribution weighted heavily against the signaller having genuine curiosity.