Rashi says that Yitzchak became blind from the smoke of the idolatrous incense of Eisav's wives. Why did the smoke not blind anyone else? We can begin to understand this by way of three stories: R' Nochum Chernobyler didn't see a non-kosher food item, the Lubavitcher Rebbe didn't see Bob Dylan, and a teenage boy didn't see an inappropriate billboard.
Based on Likkutei Sichos vol. 5, pp. 139-140.