In a study conducted in 2007, researchers investigated the link between positive and negative statements with bright and dark. In the primary task, 40 participants had to tell if a square was the bright one or the dark one after judging valence of positive or negative word that were displayed on a screen. Authors used temporary deception by telling participants that the square brightness would not be the same after each word, when it actually was. The analytical approach involved comparing mean percentage of light square responses for each word valence with a repeated-measures t test. Confounders like word frequency and color inherently associated with words were controled. Among other hypothesis, the primary hypothesis which posited that the displayed words would influence brightness perception, was supported by the results with a large (p. 368) effect size. This overview provides a concise synthesis of the most relevant results. For more details, please refer to the article page.
It is likely that the brightness of intrinsically good objects will be overestimated by the users perception.
Meier, B. P., Robinson, M. D., Crawford, L. E., & Ahlvers, W. J. (2007). When “light” and “dark” thoughts become light and dark responses: Affect biases brightness judgments. Emotion, 7(2), 366–376. https://doi.org/10.1037/1528-3542.7.2.366