Hello, yesterday I dinged 80 on my warlock alt. Atm Im using destro build for pve. As far as I know a lot of well geared locks use Demo specs for 3.3 raiding? Is demo good for half blue geared lock? Or maybe shall I try afli?
Disclaimer: The following is terrible advice in the long term. Plus it doesn't really answer your question regarding Demo.
If your intent is to join many random dungeon finder groups for badges for gearing up, your best bet to avoid nerdrage from pugs is to go Affliction for improved Seed of Corruption AoE hence better numbers on the meters.
If you're planning to run a bunch of dungeons with your mates who are reasonable people, have patience and understand that every alt starts as a work in progress, you will probably find yourself reaching a point where you can contribute significantly sooner, by staying Destruction. Destruction is both easier to learn and a little less gear dependant.
@Troy - the number of tanks in my guild who complain on vent about Seed of Corruption hitting the boss before they do is at 80% and climbing. Good tanks pay attention to this and nerdrage just as much, just not to you