> This should be a discussion on how valid it is for police to profile people.

Exactly - though in this case I'm not sure what that means - if they 'feel more alert and suspicious' - that's just going on in their head ( pretty difficult to control that ). If on the other hand it means you are constantly getting stopped and searched that's another issue - but then you could argue that's then argument about the stop and search rules in whatever country.

ie what counts as reasonable grounds for the police to take concrete action.