As you've probably noticed recently (sometime after 3.1 though I don't run with a warlock often so I cant be sure when exactly) Blizz did a stealth nerf (not in any patch notes as far as ive seen) so that the scorch debuff is overridden by Shadow Mastery, the debuff given by Improved Shadowbolt (warlock tier 1 Destruction talent).
Basically a QQ post, I find it annoying beyond all means. If theres a warlock with it in the raid, we have to depend on him/her to keep it up at all times, which might not happen, depending on the warlock's skills. If I see it drops off and I rush to get a scorch, it might live a few seconds then get eaten again by SM, which will again drop after a while if the warlock is slacking. Dps loss all around.
Argh!
Edited, May 15th 2009 6:11am by Amaiya