I've seen this too. Some people use thumbnails as a way of attracting viewers to click...but I don't really see the point since the disappointment in most cases only generates either comments that has nothing to do with the image itself, or the viewer will leave without making any comment at all. And thumbnail size as art is usually called "miniature"...while a thumbnail is suppose to be a preview...at least to me it is :D

"Keep smiling, it makes people wonder what you're up to."