One day in the car after delivering his shiur in Yeshivas Kol Torah, Rav Shlomo Zalman asked the driver to pull over in front of a kiosk where he went out to buy a candy bar to cheer up a child whom he was on his way to visit in the hospital.
After buying the candy, on the way back to the car, Rav Shlomo Zalman started to examine the candy bar and turn it over from side to side. The person accompanying Rav Shlomo Zalman assured him that he has no need to worry since he knew that this candy bar had a very good Hechsher. "I wasn't looking at the Hechsher", said Rav Shlomo Zalman. "I was checking if the candy was good!" (Aleihu Lo Yibol YD 143)