Can't help much on Kara since I havent been to kara yet but about the guild bank, if you're trying to find a way to "trace" the item, then you can't, unless you're a GM. What you can do if you are REALLY strict on this is get the person requesting for items to tell you what they need it for. Usually it's to craft something or requesting for an equipment that's an upgrade. Then ask them to craft the item in front of you or equip the gear in front of you. If the ingredient is something that he/she already has but requesting it so he/she can sell the extra one in the AH, then well, if they are willing to go through such troubles then you might as well let them compromise their integrity. However, you can keep a list of who has requested for what and when, if someone is requesting too much then you can keep an eye on him/her.

For rare items that only drop from guild raids (e.g. lava core during pre-BC), usually officers will get the guild crafter to craft it and choose who to give it to first.

But my previous guild had the problem of having too much trash in the bank than people falsely requesting for stuff haha.