Interesting thread. WRT type ratings and medicals, in the US I'd look up the medical dates on the FAA online registry database and the type in the online DPE database. Of course this isn't 100% that they haven't expired, but typically examiners are well-known quantities in their local area (including which ones to avoid because they are, by nature, disagreeable people).
While I do teach students to check certificates (for example if you are flying with someone and don't want to take responsibility as PIC), I don't know that many would have the cajones to card the examiner. Perhaps I should start doing this.