Unveiling Surveillance: Can an Intelligence Man Identify Three Watchful Eyes in a Crowded Cityscape?

This scenario is certainly plausible, especially in the world of intelligence and espionage. People trained in fieldwork, such as spies and intelligence officers, are often taught to be hyper-aware of their surroundings. They're trained in skills such as behavior analysis and surveillance detection, all of which assists them in spotting unusual activities or patterns. In your given situation, an intelligence officer might be able to identify individuals who are observing him based on their behaviors or subtle cues, like someone consistently appearing in his vicinity (the park guard or the man at the tram station), or someone who seemed to be overly interested in his activities (the man on the metro). However, it's worth noting that while it's possible, it's not always guaranteed. The success of such identification would greatly depend on the skill level of the intelligence officer and the subtlety and skill of those conducting the surveillance. Even for the most trained individuals, human error or well-conducted surveillance can lead to nondetection.