What is the ruling on one who calls a religious person "mutawwi'" or "shaykh," and what is incumbent upon the one so addressed?

There is no harm in addressing someone who adheres to the Sunnah (definition) with titles of veneration for his following of the Prophetic guidance, such as "Ahl al-Sunnah" (People of the Sunnah), as people judge by outward appearances. And whoever has this as his outward appearance, then he must rectify his inner self to conform to the religiosity he displays, and to live up to the good opinion others have of him, and to be mindful of Allah, who looks at hearts and deeds.