Is it obligatory to respect elders, even if they show little respect and manners?

The Shari'ah encourages honoring and revering elders, as confirmed by the words of the Prophet, peace and blessings be upon him: "Indeed, part of glorifying Allah is honoring the white-haired Muslim..." and his saying: "He is not of us who does not show mercy to our young and respect our elders." Elders should be honored by showing them respect in gatherings, being gentle with them, and having compassion for them. As for the elder who is ill-mannered, or openly commits immorality and transgression, or is an oppressive tyrant, he does not deserve the same reverence as the righteous. However, their age should still be taken into consideration, and they should be dealt with wisely and gently.