What's actually happening is what should happen - people go quiet and look at the walls, or out of the window, or check their watch, or overly carefully clear their throat, and shuffle their feet slightly, embarrassed that somebody's actually come out with this clichéd lead balloon without having realised beforehand that it will simply fall flat and make them look a bit of a dick. But maybe if it's ignored for long enough, everybody can pretend it just didn't happen, or, failing that, the ground will open up and consume everybody that witnessed it, much to their shared relief.
Nah, you've got the reason wrong. I've been making the joke for a while, as you say, and the reaction used to be exactly what jrockway said: a bunch of people being consumed with righteous rage that I could slander such an upstanding institution.
These days, they just awkwardly shuffle their feet and don't say anything, because it turns out we were totally right about the wisdom of trusting your money to the Magic: The Gathering Online Exchange.