Sounds highly dubious. Which scientist would seriously try to hunt ghosts? Doesn't sound like something which could get published.
Of course ghosts do not exist. We cannot imagine to not be anymore one day so we make up this kind of stuff. But from a scientific point of view you could not say that they do not exist, just like you could not say that unicorns to not exist. There might be a funky planet after all where these horses actually roam through the forests. Doesn't mean that you cannot doubt the sanity of anybody who thinks that unicorns are real, merely means that the scientific method is fairly rigorous and doesn't always allow you to say the commonsensical thing.