The first layer of the image in an image is what it is about, a tree, a house, a car. The second layer though is what general mood it evokes. Even if your images depict the right thing, somehow they do not feel right, and it is hard to pin down why. Here is a check list, I am exaggerating on purpose. 

• Cheesy, tacky, not real, fake people
• Something aggressive, violent, scary
• Things are gross, ugly, not pretty, repulsive
• A bit too racy
• Girly, cutesy, childish
• Dark, somber (including colours)
• A closed, trapped setting
• College humour that is actually not really funny
• Cliche: ice bergs, dominos, 

I am exaggerating on purpose. That image of the apple pie is probably not "gross", but subconsciously, there is something not tasty about it. The image of the solider is not violent, but somehow a military association sets the wrong tone of the presentation.

The opposite is also true. The best images can uplift your mood and somehow makes your feel right. Images can set your mood pretty much like a painting / piece of art can.

If your image does not feel right, it probably is not right.