This painting by Leonid Afremov has, a couple of times, appeared on the front page of the website Reddit. Reddit has a system for voting up submissions, so something that a lot of people like will rise to the top. It is relatively rare for any painting to be upvoted so highly, especially more than once.
From an artistic standpoint, the painting has little to offer. Everything that is good about this painting is good on the surface. It uses a variety of simple tricks to attract the viewer. It is the visual equivalent of McDonalds' food-- it tastes good because it has abundant fat and sugar, which have a direct connection to the pleasure centers in the brain. Here are a few of the tricks:
The colors are all saturated.
There is a rainbow progression from yellow at the center of the light, through orange, red, and purple to blue in the sky. This is a comforting pattern.
The lines of perspective and brighter center draw the eye to the couple, who are expressing love and comfort. (The artist doesn't really have a great feel for perspective, though. What is going on with that bench in the foreground?)
There is a cute dog.
The reflections in the puddles and canal make a kind of symmetry.
The palette-knife strokes allow pleasing contrasts between adjacent colors, and add a kind of visual texture to the image.
These are predictable responses of people to images. Good artists make use of the same techniques. Van Gogh's Starry Night, for example, uses some of the same techniques of contrast, saturation, and lines guiding the eye. I think that anyone, human or otherwise, learning to be an artist has to pass through the stage where they are learning these tricks. Eventually, they become tools that can be deployed as desired with an understanding of the effect they will have on the viewer, in order to get across a more subtle emotional message.