In plain words
Services sold under this name vary widely. We do not read criminal forums. We check whether a firm’s own addresses appear in monitored breach databases, and we read only addresses at the firm’s own domain.
Why it matters to a firm
What matters is not the label but what is read, how often, and how fast a new finding reaches the person who can act on it.
The check behind the finding
Ask any provider which sources it reads, how often, and whether a person reviews a finding before it is sent.