No, no single experience, in fact, too many that it gets frustrating. Would love to say it is a misfounded claim, unfortunately it is not.
A total of 4 HD7950 and 3 HD7970s made by Sapphire (2L and 3L) gone bad on my watch. Almost all of them stopped working after the PC got moved one way or another. The worst of them, however, is the one that just quit in the middle of a game. No other brand has done that to me.
So 7 Sapphires gone bad of aprox 20 I owned. Pretty high percentage considering that most of their HD7950s / HD7970s at some point developed issues. I have owned more Powercolors than Sapphires, similar PSUs, similar treatment, and only 2 gone bad at some point (Both of them HD7970 with the swirl cooler, nice and quiet, but flimsy. The turbo duo cooler in the newer ones is in a different class)
Oh, and for those you claiming that the Sapphires are not fragile, have you owned others brands, or have even had the chance to hold a card with the same GPU made by someone else? Compared to the powercolor turbo duo (metal backing plate), the Sapphires R9 280 / R9 280X feel flimsy but you need to have held both of them to make a valid comparison. As flimsy I mean not only more PCB sag and bend, but also more torsion in the cooler (less rigidity ) The XFX R9 280 / R9 280X, while not a metal backing plate, it is very sturdy in the cooler.
In the past, one of our resident AMD haters even posted a chart with the video cards most RMAed. At the top? Sapphire HD 7950. I don't remember the exact number, but if you invoke certain resident AMD haters, one will chime with a link to the chart. The RMA process should also tell you something, send those Sapphires HD7950s for RMA, you get a refurbished card, which leads me to believe they have a lot of them...
There you have it, while 40+ or so video cards don't provide rigorous proof, it sure amounts to more statistical significance than just owning one or 2. So those of you with Sapphire HD7950 still alive, consider yourselves lucky.