This is absolutely true. There could be a thousand years of a million people noticing similiar pre-earthquake events, and according to modern science, if those observations were not standardized and correlated into a reproduceable model and peer-reviewed, there would still not be a "scientifically proven predictor of an impending earthquake."
On the other hand, "in 1931 the mathematician and logician Kurt Godel proved that within a formal system questions exist that are neither provable nor disprovable on the basis of the axioms that define the system. This is known as Godel's Undecidability Theorem. He also showed that in a sufficiently rich formal system in which decidability of all questions is required, there will be contradictory statements. This is known as his Incompleteness Theorem. (http://www.exploratorium.edu/complexity/CompLexicon/godel.html)
In other words, Godel scientifically and mathematically proved that there are truths which science can never prove, and untruths which science can never disprove, and therefor science can NEVER be the last word on the truth.
So I'd say, when a hundred square miles smells like sulfer, and the wind is blowing the wrong direction, and th media keeps talking about dead fish instead of sulfur, and people report (in a non-peer reviewed manner) the same smell numerous times throughout history before large earthquakes, well, that's what the government is FOR - to tell you whether to worry. And look - the government is telling you not to worry.
So that's that.
Having studied the science, as well as having lived through two major earthquakes plus countless large earthquakes where never a strange odor was detected prior to the earthquakes, I think I'll stick with scientific facts and leave the backyard fence, scare mongering to others more proficient in same.