Specific notes for common raiding thingies:
Darkmoon Card Crusade: Any spec, but especially affliction, has a really easy time keeping this stacked, and getting it stacked while the tank builds threat, because we have spammable low-cost low-agro long-range curses. It's often worth the time to debuff a target to keep the stack rolling.
Clicky Trinkets and affliction builds: Clicky trinkets should be saved for when all of your DoTs are going to be refreshed in a small window. If at all possible, on 20-second clickies, try to double-tip corruption and unstable affliction. It's worth saving the trinket for a few seconds, it probably won't cost you an extra activation.
Procs and DoTs: Recasting a DoT and overriding a previous one is never, ever worth it, no matter how awesome your proc is. You lose half a tick on average, and the damage gain from the amped DoT is not worth that half a tick. For example, 2pcT4 proc is 135 damage. Over the course of a corruption this comes out to 170ish before debuffs. The lost half-tick of corruption is 250 at that gear level. Ignore your procs, and keep casting as if nothing happened.
In a similar vein: while you want as close to 100% DoT uptime as you can manage, you want to absolutely avoid clipping DoTs, and also avoid waiting for DoTs finish. If a DoT is half a second out, cast a shadowbolt and refresh it late.
The exception is UA, and untalented corruption: it has a cast time. Remember this.
Finally, affliction builds actually do scale really well, it's just that they only scale with damage since crit is marginal and we hit-cap easily. Higher-end gear tends to spend a lot of itemization points on crit and haste, which help destruction far more. It's not exactly a matter of scaling, it's a matter of scaling with the itemization that we will actually encounter in higher raid settings.
And yeah, I hear enough about 0/40/21 that it should probably be mentioned. It plays essentially like a felguard build with a sexybus instead of a felguard, but it gears more for crit. Example spec(?):
WorldofWarcraft.com -> Info -> Classes -> Warlock -> Talent Calculator
As far as affliction builds go, I would list this:
WorldofWarcraft.com -> Info -> Classes -> Warlock -> Talent Calculator
as the absolute bare-bones affliction build, with most of the rest being determine by gear, playstyle, and raid group composition. You will note it's not a viable build: it requires fleshing out. I don't know how to make wowhead's talents do that.