I only do Flashpoints for the story and the experience points. I always select greed and feel bad whenever I still manage to win an item roll that just on GTN. Great for credits sure but my needs are being met by simply doing the flashpoint with a group and I want to make sure my teammates are getting their needs satisfied too. Today I saw someone reject the loot option. I wanted to ask how they did that but wasn't sure if that would be against etiquette. My fault for being a bad player but two months in and I still learning how to play better.
It's not completely intuitive but if you don't want to roll on it at all just click the "x" in the top right corner of the loot window to pass on the loot entirely.