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Bugger indeed.
Double bugger if its likely that the vendor knew of the issue and sold them on regardless.
I'm sure it does happen.
But are you sure they're warped ?
I'm of the opinion that in many cases of supposedly "warped" discs, the pulsing and juddering is down to localised degradation of the surfaces rather than warping.
My own std discs had 3 or 4 consecutive advisories for pulsing and this was very noticeable at slow speeds (walking pace) but was fine at higher speeds.
A dti check revealed no warping whatsoever.
I did the usual bobbin cleaning (to no avail).
I then cleaned up the braking surfaces using first scotchbrite and eventually ending up with 400 grade wet 'n dry paper wrapped around a flat block.
This reduced the pulsing a little but it was still present.
A couple of days later came the ukmoc trackday at Mallory and the brakes had a right good workout, after which I noticed that the pulsing had reduced significantly.
Further hard use of the brakes resulted in further improvement and after a few weeks the pulsing had totally disappeared.
Since then I've done 20k miles or so on these discs and they still show no sign of pulsing (and the mot advisories have ceased).
The general theory seems to be that new discs require a certain surface conditioning (sometimes referred to as "tempering") during which there is an interaction between pads and disc (possibly involving deposition of pad material on the braking surfaces).
My reasoning is that either...
1) This initial surface conditioning is improperly carried out in the first place, due to the brakes not being used hard enough to get them consistently hot enough.
2) The surface conditioning becomes degraded somehow .. possibly due to either holding the brakes on hard when they're hot after braking to a standstill or perhaps due to localised corrosive effects from standing with wet pads after a rainy outing.
Either way I would suggest cleaning them up (carefully and evenly) using fine wet 'n dry (might as well clean the bobbins too while you're at it) and then going out and giving them a damn good workout with repeated hard braking, to recondition the surfaces (making sure not to hold the brakes on after coming to a halt, to avoid localised hot spots).
That assumes, of course, that there is no significant measureable warping ... which I would be prepared to wager on.
Its not guaranteed to work but it certainly worked for me.
And it was an educational process too.
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