Yes, many of these rumors are simply untrue, and there are certainly sites out there who will make stuff up or print preposterous rumors as fact. But I think there are also a lot of cases when things get reported that were true at the time, but then end up changing by the time the movie comes out.These types of articles and journalists haven't been right about anything so far, and given the quantity of false rumors we've had, I think we should ignore them going forward.
E.g. the story about Force Awakens opening with a shot of Luke's lightsaber floating through space seems like a false report now, but it was actually in the script and parts of it were even filmed before Abrams decided to change it. If you're gonna read any news stories about upcoming movies, you're gonna have to accept that a lot of that stuff won't have anything to do with the finished product.
But as far as movie scoops go, some guys like McWeeny, Devin Faraci, and Umberto Gonzalez have a pretty decent track record, even if they can't help being wrong a lot of the time.