I know we love to complain, but across ten or so flights in the past month as a GS stuck in economy (a string of bad luck + hub-to-hub routes), I've had no issues with this benefit. FAs acknowledged my status, expressed empathy I got stuck in the back, and on all but one flight, I was never charged for any drinks despite having three or four. On a couple occasions, the economy FAs even proactively brought me a couple extra minis of my preferred Glenfarclas. I have no complaints.