Judges and juries must draw their own conclusions from the evidence. Estimates of the end of a moving object or the source of an odor are allowable opinions. I move that the testimony be stricken from the record. Because they are very unreliable, these statements ordinarily may not be used to prove the truth the matter asserted. For reasons of necessity, a set of exceptions allows certain types of hearsay to be introduced.
Hearsay is a very tricky subject.
A few objections which may arise in the case. Joe is being tried for murdering Henry. If offered to prove that Joe lolled Henry, this statement is hearsay and probably would not be admitted over an objection. Instead, it is being introduced to show that Henry had warned Joe by shouting. Objection, your honor.