Personally, I think the Loch Ness monster legend is all nonsense. The whole point of the exercise from the beginning was to generate more tourism in that area. I think some people may have seen something they couldn't explain right away, but it was probably something normal that just looked mysterious. I've seen carp that were massive compared to other fish, but they were still just carp, not living dinosaurs. I'm sure I could take a picture of a lake sturgeon and make it look like a plesiosaur at the right angle.
As much photographic and sonar equipment there is around most of Loch Ness, I would think someone would have captured a more convincing image by now. They even take a fleet of boats out once in a while and scan the bottom of the entire lake. I've heard there's a fairly realistic movie prop from an old Loch Ness monster movie that surfaces every once in a while. Maybe that's what people are reporting these days.