If I didn’t love the writing of Robert E. Howard I would probably never have bothered with any Conan pastiche. As a matter of fact, those Conan novels on store shelves in the ’70s and ’80s made me so skeptical of Conan that I didn’t try Robert E. Howard’s fiction until years later. I wrongly assumed that because the series looked cheap and mass produced that Howard’s writing would sound that way. (Robert E. Howard, of course, had NOTHING to do with the mass marketing of his character, having been dead for decades before that marketing was carried out by other hands.)
You can fit the sum total of all the Conan that Howard wrote (including some fragments and rejected stories) into one large hardback. That’s not a lot of fiction about such a great character, and so for decades people have been trying to create new tales of adventure starring Conan, mostly because they wanted MORE!
What makes those stories pastiche instead of fan fic, I suppose, is that many of these writers were paid to write it and the result was distributed widely. You would assume that meant that the work was well-edited and had some kind of consistency, but a lot of people, me among them, would tell you you’re wrong.