Man of Honour
Just been had by my local CeX shop today, noticed a 2GB stick of DDR2 RAM in the window for £3, bargain I thought perfect for fixing up an old machine. Got home tried to insert it into a slot and noticed the notch didn't line up, googled the serial number and it turns out that it's server RAM. I wouldn't have bought it if I'd have known but it clearly stated "Memory - Desktop" on the display stand and also on my receipt!
Shysters.
I would chalk that down to ignorance rather than deceit - if it's the shorter wider rectangle it's laptop memory and if it's the longer narrower rectangle it's desktop memory.
I'd also chalk it down to "it's too cheap for us to bother testing it, who cares?"