Last night in a PVP battle out at TM, I started using this, I was able to see the Rogues. They were grey and see through, similar to when friendly rogues are stealthed, only they had a Red label above them.  They are pretty hard to see, but it worked for me, and my party. Maybe a patch changed this effect? Maybe you only have a "Chance" to see them? I would say that we saw all of them, but you don't know, what you can't see?  I'll keep trying...