Regarding "real merged to real, fake labelled as fake", I've tried two approaches over the last couple of years and have this experience to report:
A. If George Anderssen Smith is a fake person with no real counterpart, then it's good to keep a profile, clearly label it a fake, and provide thorough documentation as to why it's fake, because mang people have been sold a bill of goods that they are descended from GAS, dragonslayer. We owe it to them to tell them, no, you have no such ancestor. And profiles like this need to be stripped of all links to parents, spouses and children, with the links continued in the narrative; Fake people were never born, had no parents, spouses or children.
B. If there's a real George Anderssen Smith as well as a fake one, I've tried maintaining two profiles, and my experience is that it causes confusion. People try to add fake information to the real profile and real information to the fake one even though I've put links back and forth in the profile. Therefore I recommend that there be just one profile for the real person. The Biography section should contain only real information with inline citations. There should then be a ==Research Notes== section. Now, what one is documenting is not the life of a person, but the life of a fiction. Who started the fiction, what did the fiction comprise, and how did it develop. That way all the fictional "facts" get included, but as part of a narrative about how the fiction developed.
That way it's all on the same profile, and someone seeking to add a fact which is actually fictional will see how their "fact" isn't really a fact" and they don't add it.
IF, of course, they read the profile. I've run into people who happily make changes in the data field without bothering to look at what's in the narrative. Haven't figured out how to handle that. It's one reason I seek to be on the trusted list of many profiles I work on, so I get notified when it gets changed.