Dogs can read signals -- look at sheepdogs; they understand hand movements for left and right. Dogs are no fools, you know." He paused. "Well, some are. Some dogs are truly stupid, Ulf.
The quote highlights the intelligence of dogs, emphasizing their ability to read and respond to human signals, specifically using the example of sheepdogs that can follow hand commands. This illustrates that dogs possess a keen understanding of communication cues, showcasing their cleverness and trainability.
However, the speaker acknowledges that not all dogs are equally intelligent, admitting that some might be lacking in smarts. This ambivalence adds a touch of humor, suggesting that while dogs are generally perceptive, there are exceptions that can be amusingly perceived as "truly stupid."