Heels with no credibility. This is often a WWE thing, and since 2002 is fresh in m mind, one of the worst examples I've ever seen is Chris Jericho.
He spends most of 2001 as a highly credible champ who could beat Austin/HHH on any given night. When he finally wins a big one by defeating Rock for the WCW Championship, it involves Stephanie fukkery and hitting his finish on a chair. The night he wins the World and WWF championships, he beats Rock with a Vince run in and a low blow, beats Austin after multiple ref bumps/Vince/Flair/Booker run ins followed by a belt shot.
The rematch with Rock at the Rumble has Lance Storm/Christian run ins, a ref bump,. heel ref refusing to count for Rock, low blow, exposed turnbuckle, and feet on the ropes. He beats Austin at No Way Out after multiple ref bumps and the NWO running in.
After he loses the title, he's on Smackdown having to cheat to beat rookie John Cena and THE BIG VALBOWSKI. On Raw, he has to cheat to beat Maven even as champion. I'm pretty confident Jericho doesn't have a single decisive, semi clean win all year. There is absolutely zero reason to take him seriously as a competitor. This dude had to cheat to beat LOW carders even as double champion. His title run was dog shyt not because he was picking up Steph's dog's shyt, but because he had no credibility whatsoever.
It's okay to have heels be established as just better than some of their opponents. They can stay heels and get clean wins. You don't need a bunch of fukkery and territory bullshyt to "keep the face strong" every fukking match.