I must be totally oblivous because after more than 20 years travelling in premium classes with or without shiny bits of plastic I have never noticed any of this sort of behaviour from the other queues.
I must add though that I also travel in economy, and I simply grin and bear my lot and go back to FT to figure out if there's a way to remedy that situation for the future.

Only once did I use the business class line when I was technically not entitled to it - the economy line at Ethiopian Airlines in Beijing was uncomfortably large, and I sauntered up to the C line with a business associate who was travelling in C. But I looked the part, so no protests and they checked me in without problems. I did feel a little guilty though - but only very little.