Being a Thief myself...I'm allowed...I hate seeing people in the same job that have no idea what they're doing. Besides, I've complained enough about tanks that can't tank right. Time to complain about thieves who can't umm...thief right.
I can understand why many thieves early on use swords rather than daggers (It hits harder initially). After a certain level, (mid-20s) it's time to stop. Especially if you aren't even stacking Fast Blade and Sneak Attack together. (When you're level 29 and your Sneak Attack usually hits in the 60s, you have a problem.)
Sneak Attack and Trick Attack are a little more complicated than just using a macro to activate it. If you don't know what you're doing...ask a thief who does. Thieves tend to be a tight bunch and will usually help one another out if asked nicely.
Stealing is a wonderful ability, even if it fails a lot. Steal every 5 minutes if your inventory allows. It doesn't hurt.
There's a reason that thieves are one of the few classes that can equip boomerangs....we're pretty good at using them...and it doesn't cost anything for ammo....buy one..they aren't that expensive. There's no reason you can't be a puller.
When partying with another thief. Stand on opposite sides of each other. Especially if you're both subbed WAR. One THF SAs, then provokes, then the other does the same, and finally the tank (if he's been provoking properly the whole time) can provoke it again to take the hate. This way you have a greater chance of hitting all your Sneaks.
Don't use Trick if you don't know how it works...people will laugh at you...I know I do, and I don't even have the ability yet.
Not all weapon skills combo with SA. Even if other party members don't notice, your fellow thieves will, and they'll be sure to laugh at you for that too. (i.e. Don't try and stack SA and Red Lotus Blade)
That's all I can think of. If anyone else has anything else to add, or wants to complain about another job. Feel free. I need something to read at work.