Having just started back into running instances and raiding (my original computer could not keep up with the graphics on even the lowest setting.) I had to make those decisions that everyone from time to time have to make. Should I roll need or greed.
Myself, I've always kept a hard true rule. If I need it then I had better be willing to equip it right then and there. Many groups, especially with BOE gear that is available in Raids and instances require that you equip it right there. Keeping the people who will need on everything, even if they already have a version of it equipped. It work usually, though occasionally people will slip through the ninja cracks.
But as a seller of gold making merchandise, Is it okay to need on something that you specifically know you will not equip but are going to sell. I ran into this while running the first of the Dragon soul instances. [Bindings of the End Times] dropped for our group. Needing to make a quick decisions I went ahead and pressed greed on the item, winning the random number generation contest. A excellent 1k gold in my goblin pockets. But it did make me wonder whether I had actually won it fairly. Yes I did the right thing to roll greed knowing I was going to sell it (I run an arms warrior currently) and it was not high on my awesome list of items to get. Scrolling back through my logs I saw two people who completely passed on the item. I can only presume that they did not roll simply for either misreading the BOE status of the item, or that they just assumed I would roll need on it and did not want to waste the time.
As the DS raids and instances continue on, and the BOE items drop, presuming that someone will automatically take the item just drains possible money out of your pockets. Any run, anything drops, press greed (or if you legitimately need the item, press need). It's either that, or go ahead and send me all your money now, cause your just giving it away to someone else.
Good luck and good hunting
Upgrade your game, and your sales