Seloco
I have flown those 757s with the missing fairings and it is a difficult decision over whether to tell the punters or not.
Usually it comes down to the fact that only a few people can actually see it from their seats. In a classic case of "a little knowledge is a dangerous thing" telling all the passengers tends to scare them and the fear of flying passenger wants to get off.
Best bet is to explain all the details to the crew, so they can sound knowledgable and convincing when asked by a passenger.
Worked for me
T'bug