They pretty much don't exist for any practical use, due to thunderforged gear. You're far better off finding the difference between potential non TF otherwise BiS pieces (such as the ring off Mag) and comparing that to another piece that may not technically be BiS but be thunderforged. Example, the 535 heroic non TF axe off tortos, if thunderforged would be BiS. But the 541 H-TF axe off Jin, although not BiS, would still be better (Most likely, depending on how you can handle the hit/exp due to other pieces.)
Even sim-c's BiS list I'm not quite sure is accurate. For example, it shows the 541 bracers off Horridon (haste/exp) as being better than the double crit bracers off Jin, despite the fact that you get over 900 crit+320 from the yellow socket. Maybe at that much crit, it starts to lose in value or maybe because wowhead shows (random stats) simcraft can't handle it, IDK, but I wouldn't take it as gospel.