The quote expresses frustration with the precision with which witnesses recount events in mysteries, specifically criticizing the reliability of their memories. The speaker feels that the witnesses are simply making excuses to avoid revealing the truth in front of detective Poirot, undermining the credibility of the entire narrative. This skepticism highlights a broader theme of questioning the integrity of human memory in high-stakes situations.

The speaker's disbelief in the accuracy of witness testimonies challenges the notion that people can confidently recall details under pressure. This statement reflects a humorous yet cynical take on how often witnesses might exaggerate or misremember facts to fit the expectations of investigators, ultimately casting doubt on the conclusions derived from their statements.