Once as I was just politely trying to explain CCing to group members before we even started.
Spend a minute talking to the people in your group if they don't understand the dynamics. Worse-case scenario is you wipe a couple times, which makes it more fun when the group gets it together and triumphs.
No - worst case scenario is the group patiently listens to your explanations, then repeats all the errors and you wipe again, as if you'd said nothing at all.
I too spent some time explaining CC to a group and explained that the droids in the pull needed to be CC'd and that I (the tank) needed to make the pull.
After Leroy 'Marauder' Jenkins had made the pull for the third time, and between the three characters with droid CC, not one droid was mezzed, I gave up.
Obviously, people need to learn the game, but that can be from listening and learning "on the job" so to speak, from people with more knowledge and experience. The problem is with those who don't want to listen, have no interest in learning and think they can zerg through all content with mediocre gear. Hardmode FPs aren't particularly difficult, but they do require basic MMO tactics and something better than tissue paper armour and pop guns.
 False Emperor - Didn't even get off the hangar deck.