>>5817874In my opinion, lack of expressiveness. Confident /beg/ drawings carry a certain amount of "soul" because of their confidence/the fact that they enjoy doing whatever they are doing.
Often, people who are more self-conscious about being /beg/, or who are too analytical while drawing, tend make less expressive, more timid work.
For more experienced artists, the analytical side has become second-nature: as long as they have something to say/that they enjoy what they are doing, you should expect some "soul".
So what makes art soulless is the attitude, the mindset of the artist. Traces of the mindset are visible in the artwork: brushwork, value scales, insecure strict-copy-mode, etc.