
Sincere debuted in World Championship Wrestling (WCW) in 1992, where he went by Johnny Gunn. He achieved some of the most notable moments in his career while teaming with Tom Zenk. At Halloween Havoc 1992, Gunn partnered with Shane Douglas and Tom Zenk to defeat Bobby Eaton, Arn Anderson, and Michael Hayes.
Gunn later joined Extreme Championship Wrestling as Tom Brandi, and teamed with Tommy Dreamer to capture the ECW Tag Team Championships. They captured the titles from Johnny Hotbody and Tony Stetson in only nine seconds. Less than a month later, the pair would lose the titles to The Tazmaniac and Kevin Sullivan.
He then went to the World Wrestling Federation (WWF), debuting in July 1996 as Salvatore Sincere, a villainous stereotypical Bronx Italian/Mafioso character clad in pink and white who falsely claimed to be sincere and to "love" everyone. He appeared at the 1996 Survivor Series and In Your House: It's Time, where he wrestled in dark matches. He also worked matches with some of the WWF's top names at the time, including Shawn Michaels, The Undertaker, and Rocky Maivia during his debut match in the WWF with Salvatore). He briefly feuded with Marc Mero over his valet Sable in 1997. During this storyline, Sincere began wrestling under his given name Tom Brandi after Mero called him a jobber. Sincere later would go on to win a match against Mero by countout. After going by his real name, he participated in the 1998 Royal Rumble match, lasting a matter of seconds before being eliminated by Cactus Jack and Chainsaw Charlie. He lost to Jeff Jarrett in his last televised match on the March 17, 1998 episode of Monday Night Raw. Brandi left the WWF that April.