Appeal to flattery[1] is a fallacy in which a person uses flattery, excessive compliments, in an attempt to appeal to their audience's vanity to win support for their side.
[4] Flattery is often used to hide the true intent of an idea or proposal.
Praise offers a momentary personal distraction that can often weaken judgment.
[3] Examples: A refusal which does not deny the compliment could be formulated thus: "I may be [positive attribute], but that doesn't mean that I will [perform action] for you."
It is not necessarily a logical fallacy, however, when the compliment is sincere, and directly related to the argument.