Here's the thing, if there were massive failures, we'd see nVidia talk about taking a financial hit due to increased RMA costs which never surfaced. If they claim it was test escapes then that may be it and if it was, then that is certainly their fault but at least there was RMA as an option.
Companies can hide that stuff in their finances if they need to. However, since these expensive products are not their super high margin and high sales volume products (not to mention limited launch supply in general) even if the failure rate was an astronomical 10% given the low volume (comparatively) it wouldn't be THAT big of a mark on their finances. Of course if it was that high they'd have other things to worry about. Still, with multiple people getting 2+ bad cards during the RMA process I bet on the failure rate being notably higher than normal.