Pseudoscientists often say, "You can't prove I'm wrong; therefore, I'm right." The mistake that they are making is where they place the burden of proof. In the American court system (I know that it is different in other countries), you are considered "innocent until proven guilty." This means that it is the job of the prosecutor to prove the defendant guilty. Another way to say this is that the burden of proof is on the prosecutor. In science, the burden of proof works in a similar way.
If I purpose a new hypothesis, say that flying unicorns exist, it is my job to prove it. The burden of proof is always on the person proposing the new idea. This is done for two reasons. If it was the job of scientists to disprove every claim that came their way, they would never have time to do anything else. The other problem is that vague claims like the one above are logically impossible to disprove. All you can say is that they are extremely unlikely to exist. On the other hand proving that flying unicorns exist would be quite easy, all I have to do is find one that can be studied. If you hear a wacky idea, ask for evidence. Don't let them wiggle out of that by asking you, or anyone else, to prove them wrong.