A habit I got into long ago, know the three letter airport* code of your destination and make sure that's the last code printed on the tag. A couple of times I've stopped it and said "I'm going via Toronto, not to it".
However travelling on a mixture of passes and ID tickets this was often a two, or more, ticket itinerary, and they didn't design the system for us.
*There are airport codes (LGA, JFK, EWR) and city codes (NYC). Sometimes they are the same thing, but often not.