It's not false advertisement really, just misunderstanding of the product. I bet if you complained you could get the priced reduced for a misunderstanding of the product that the person is selling.
I thought that the numbers such as 5200 meant that they were comparable to a pentium 4 in the sense that they run as fast as a pentium 4 with that frequency but they really use a different clock frequency like 2GHZ or something.
if you could overclock a processor to 5.2 stabily, that would be amazing, i dont think they can right now, but im really not sure... i think thats way out of the reach of processor's right now