When it comes to the big blockbuster films, fans will always be looking for the latest bit of news or gossip. This quest often leads to rumors that circulate about those movies, and when actual news is lacking, rumors can become the main things people talk about. A recent rumor regarding Shazam! got a lot of fans excited, and after being forced to shoot it down, director David F. Sandberg asked all fans to do their best to disregard all rumors, as they will so often disappoint. According to Sandberg...
I hate for people to be disappointed but I can't respond to every rumor. Safest bet is to not believe anything that hasn't been officially announced.
The specific rumor, in this case, was in regards to a new trailer for Shazam! that some believed would apparently be hitting the internet yesterday. David F. Sandberg responded on Twitter that this was not the case, but not fast enough to frustrate some fans who had become excited for the potential of new footage in the interim.
The rumor mill is always a dangerous place. The problem, of course, is that sometimes, not infrequently, the rumors that come out turn out to be entirely, or partially, true. This means that the next time a rumor comes out it can be given more weight than it truly deserves. People will believe it simply because it's a rumor. However, rumors are just as frequently complete B.S, and since it's rarely possible to know where any given rumor comes from, it's difficult to know which is which.
Since it's impossible to know which rumors could be true and which are crap, David F. Sandberg's recommendation is to just disbelieve everything until it's confirmed by an official source. That certainly has the benefit of making sure you don't believe the false rumors, and while you might end up not believing something that turns out to be true, that's far from a big deal. You don't really gain much by believing anything early if it ends up getting confirmed before release anyway, and if you make it all the way to the movie, you get to enjoy something you didn't know was going to happen, while everybody else saw it coming and had it spoiled.
As far as this particular rumor. It might have been spawned by the new Shazam! footage that aired on television over the weekend. Somebody with knowledge of that before it happened might have morphed it into a new trailer rumor over time. Alternatively, it's possible we could be getting a new trailer sometime soon. Studios frequently end up changing dates around for things like that, so it's possible there was a trailer release planned at one point that then got canceled.
There will probably be many more rumors about Shazam! between now and the film's release in April. Until then, we'll all have to decide how much we want to believe them.