Hogan as the real heel in his feuds has been around since I had AOL dialup and an onion tied to my belt in the mid-90s, haha.
I think it'd almost be harder to find a feud where he was legitimately the face - probably Earthquake? Slaughter is a tough one to argue he's the heel. The Dungeon ... you'd have to figure out what the hell was going on in the first place to unpack that one.
How about Shawn and Marty? Shawn didn't really "do" anything until he superkicked Marty if I recall correctly, and weeks before that, Marty rolled an unconscious Shawn in the ring to take the pinfall from Flair.
Sid and Shawn after the WM 11 was weird too - HBK hired Sid to be a bodyguard, and his job was very obviously to interfere on his behalf, so he does, which doesn't even cost him the match, HBK berates him and fires him, and Sid attacks him. And is the heel? Even watching it all back it seems awkward.