Which word describes something that causes gloom and is characterized by a lack of merit?

The term that best describes something causing gloom and characterized by a lack of merit is "dismal." This word conveys a sense of dreariness and a lack of quality or success, aligning perfectly with the notion of causing a gloomy atmosphere or feeling. "Dismal" is often used in contexts where situations, outcomes, or experiences fall short of expectations, thereby engendering feelings of disappointment or despondency.

The other words do not fit this definition as accurately. "Disrespect" refers to a lack of respect or consideration, which does not inherently relate to gloom or merit. "Distraught" expresses a state of being deeply upset or agitated, which is more about emotional turmoil rather than a gloomy quality. "Disinterested" describes a lack of interest or concern but does not directly connote gloom or inadequacy in merit. Thus, "dismal" stands out as the most appropriate word in this context.