Shift or Shock? This could be subjective

I read a book by Martin Wolf, called "The Shifts and the Shocks". In economics terms, a shock mean a economy' performance is away from its trend but will return back in the future; a shift mean a economy's trend is changed. The difference seems so obvious; however, in the real life, sometimes, it is very difficult to distinguish the difference between these two terms. The largest problem is sometimes we do not know the value of our productions. For example, if there is a rumor that using Phone A has a higher chance to get cancer, then the price is very likely to decrease forever even if the rumor is proved to be wrong. This should be a shock, as nothing really changes. However, the impact shows it is a shift, as the price has been permanently changed. This is because some people's expectations about the value of the phone have been affected permanently. If some people believe there is a very small possibility that the rumor could be true, then the public expected value of this phone will decrease. From this example, we can see that a shift occurs when the accumulation of changes in people's expectations does not equate to zero; otherwise, markets will shock around the previous trend as the overall expectation does not change.