I don't care whether a reactor has heard a song before or done research before. It's only "staged" or "fake" when they say or imply that they haven't, when in fact they have. Personally, I love it when a reactor says "I've heard this song before," or "I've seen this movie before," or "I've done some research beforehand so I can make some educated comments." Nothing wrong with that whatsoever. Just be honest. I've heard some really insightful reactions from many who are upfront about already being familiar with the content they are watching. Those kinds of videos and the analysis and discussion you get are just as valid as those where the person is experiencing something for the first time and just having something that is truly a "reaction." They're both fun, for different reasons.
What kills me is the ones that are lying. I remember a video awhile back where someone was reacting to Pisces, and like most other reaction videos, swore they had never heard the song before. There were a few tells they were lying, but the funniest was when their timing was off, and they did the obligatory eye-pop and jaw-drop--a split second BEFORE Tatiana started growling.
Anyway, as far as Doug's channel specifically, I grew tired of it a long time ago and dislike it for other reasons that have nothing to do with him having done research. But good for him that he is doing something he likes, and is building a community of devoted supporters and making a bit of money from doing that.