Man is never less sincere than when he asks, or offers, advice. When he asks it, he seems to defer to the wisdom of his friend, but really he seeks approval of his own opinion, and to make his friend responsible with him for his actions. When he offers advice, he seems to repay the confidence of his inquirer with disinterested zeal, while really seeking to bolster his own advantage or reputation.
Duc de La Rochefoucauld (1613 - 1680)
Source: Réflexions ou Sentences et Maximes Morales