>>14722441X-Pac Heat, like a lot of shit, is basically smark headcanon. X-Pac was always pretty over until 2001 because by that point DX had been dead for a while and the Invasion angle was going on and he was still doing a lot of his stuff. But even then, that was during the X-Factor run and he was a heel so it's not like you can tell if he was getting booed for being a heel or not. The "X-Pac heat" period lasted for maybe 6 months in 2001 (again, while he was a lower card heel). He got injured in the fall of that year, came back as part of the nWo in March 2002, didn't really do much except house shows and tags, and was gone by July.
Smarks like to transpose whatever weird memories they create and onto the general audience. I've seen them claim shit like Luger in his mid/late '90s run not being over or that Goldberg wasn't "that over" because internet geeks hated them due to not being workrate guys.