Is speaking about people's flaws, without disparaging them, considered backbiting (gheebah)?

As long as a person dislikes the mention of it, then it is forbidden backbiting, even if it is not a disparagement. This is based on the saying of the Messenger of Allah, peace and blessings be upon him: "Do you know what backbiting is?" They said: "Allah and His Messenger know best." He said: "It is your mentioning about your brother that which he dislikes..." the Hadith (definition). The criterion for backbiting is that anything by which you make another understand a defect in a Muslim is forbidden backbiting.