AFAIK one can't use the ASIC privilege of accessing secure areas of the airport when not on duty.
Correct. While it's drifted a bit from the OP's question, my understanding is that we are talking about people who wear their GA issued ASIC while wandering around non secure public terminal areas in the mistaken belief that it makes them look more important.
It does happen...
I can understand digging one out for a coffee/retail discount, that's by grace and favour of the retailer.