This comes straight from meta editor over at Dmoz:
“To be honest, its nearly impossible to differ between the two possibilities. In some areas we assume that submitters are nice, in others our experience tells us that they are not. We are very restricting with online-casino sites due to the heavy amount of online-casino-spam flooding the ODP. That may be unfair against honest people, but we simply have no choice.”
Putting this statement together with what Simoneaton said about how unresponsive DMOZ is would lead me to belive that dealing with DMOZ if you have a gambling site is a big ol’ waste of time.