Piltdown Man has it right:
The first thing I do is thank them for their comment. Then I have a look and then explain what I have found. If I can't see what they told me about, I get them outside to show me. To date, nobody has found anything we didnt know about beforehand but plenty of items on the MEL have been spotted by eagle eyed pax. I hope they never stop looking.
We now know FOR SURE, that a picture of the hole/defect/speedtape will be on social media before the chocs are pulled. CEOs should be making it very clear that, whilst it may be irritating to get five people pointing out the speedtape - it's cheaper than the social media meltdown afterwards, over something that was not an issue.