when you are driving past in a Police car, how do you determine whether the spotter is a terrorist, or just a spotter. Remember that it IS their job to be suspicious, and, from their point of view, how do you know the spotter is not a terrorist in disguise obtaining information.
That ought to be easy to answer. Engage them in polite conversation and see if in your "judgement" they appear well informed and genuine. Otherwise detain them for further enquiries. Police have little discretion or common sense these days. As to the entrance exam, I know a few cops and tbh, it's not much of an exam. I pleaded with one of mates not to go into the force as he was unaware they lack any officer class, lo and behold, he's bored beyond belief. Bullying spotters is the high point of a dull day for certain officers.
Best example is London City. I counted three armed Police GLOWERING at people last time I was in the very small terminal. Two at the top of the stairs and one at the door, the one at the door had THREE PCSOs who were unconsciously mimicking the macho pose clutching their stab vests at the shoulders with their beady eyes peering out from their caps as their noses were so high in the air. It was like Mr MacKay from Porridge.....pure comedy gold on one level. I don't deny the importance of the task, I seriously question the abilities and judgement of some of the people we are giving a uniform to.