In a 25-year career, A Current Affair's Ben McCormack built a reputation as a textbook tabloid reporter, doggedly chasing down suspected welfare cheats and tax dodgers and busting rip-off retailers.

Regarded as one of the Nine Network show's most senior journalists, he tracked down former Hey Dad! star Robert Hughes in Singapore and led its investigation of child abuse allegations against the former actor.

McCormack went on air to describe Hughes' acts as "horrific" and "disturbing" when the actor was finally convicted on 10 charges relating to sexual and indecent acts against four young girls dating back to the 1980s and 1990s.

But on Thursday, the cameras were flipped on McCormack, 42, when he became the highest profile arrest yet of a NSW Police taskforce that uses undercover stings to catch alleged online predators.