This happened quite a few years ago but there are so many new members on here it might raise some new smiles.

My wife at the time and I were flying in J from YYZ to LHR with BA on a Avios 241 Amex redemption and had just completed a 2 week holiday. It was summer, we were in really casual wear (sandals / shorts plus 2 weeks stubble for me) and were in the CW check-in queue. A woman joins the queue behind us with what looks like a Gold Card in her hand, eyes us both up and down whilst huffing and puffing impatiently before saying, "this is the Business Class check in you know, Economy is over there" and gestured towards a long queue.

"Thank you" we reply and say nothing else. There are two CW desks open and they both become free at the same time so we are at one and this lady at the adjacent one and we can hear everything said. The agent dealing with this lady looked at her BP and says "I'm sorry madame, you have an Economy ticket not Club World" and the lady interrupts and shows the Gold Card to which the agent looks at and says, "this is not your card, it appears to be for another family member so I'm afraid I can't accept this. You will have to join the Economy queue to check-in". My wife could not resist mimicking the exact same dismissive / pointy gesture the lady had used at us just 5 minutes earlier and said "yes, the you'll find the Economy queue is over there"