A dabo player was anyone who simply played or was especially proficient at the game of dabo.
Following the arrival of Vedek Bareil Antos to Deep Space 9 in 2370, Kira Nerys mentioned that she was going to have to remember to thank Prylar Rhit for inviting him there. Bareil informed Kira that she'd better do it soon, because "Prylar Rhit is going to be returning to Bajor. It appears he fancies himself something of a dabo player," adding, "he's run up a sizable gambling debt. It's caused quite a scandal in the Vedek Assembly." (DS9: "Shadowplay")
The same year, Jadzia Dax met Will Riker at Quark's, later describing him as "quite a dabo player." (DS9: "Defiant") It was also during one of Riker's visits to DS9 that he became, according to Quark, "the only man ever to win triple down dabo at one of my tables," leaving Quark indebted twelve bars of latinum to Riker, which he comped with vouchers. (TNG: "Firstborn") In 2371, during a visit to the Deep Space 9 by Tom Riker (posing as Will), Dax teased Riker about hoping he wasn't there for "another loan," reminding him how she had staked him three strips of latinum when his winning streak ran dry. (DS9: "Defiant")