Works of art that express a dull/weak tone might depict characters that are physically and/or emotionally exhausted. Beyond representation, stylistic elements such as dirty, muted colors, minimal rendering of form, erratic edges, partial outlines, and/or somewhat sloppy paint application might lend a dull/weak tone.
An artist might impart a dull tone to a piece due to his or her own emotional state, or the artist might choose to evoke this tone as a reflection of the characters being portrayed. A dull tone might also be adopted to suit a piece meant for a setting or purpose that demands dullness.
Featured: The Sofa by Henri de Toulouse-Lautrec.