I'd say it's a very easy to verify question. If someone is experienced in interviews (you can usually tell that's the case) they might talk a lot about the stuff they did, but they will have nothing to show. Usually when you're excited about something you will have <i>some</i> proof, or will know enough details that it's easy to confirm. For almost all people I work with, it's enough to google their name to find their projects / blogs / ... everything the employer would be interested in.