When I lived in Scotland, I so did. Although that might have something to do with the fact I was ages 4-7 at the time.
And when I visited Loch Ness, yeah there were quite a few tourist attraction places and areas where they showed you pictures as well as recordings of 'sightings'. I even have my Nessie T-shirts still!
On a more serious note though now, I don't. The pictures could be of anything really. And also, why would there be some random 'monster' in some random lake? I suppose it's an entertaining legend-type thing to believe in when you're little or believe in that sort of stuff.