I've beer reading this for a while and thought that it's finally time for me to add my own story.
Went into group finder for a level 55 HM on my healer sage with my friend, who played a DPS.We got Hammer Station. This must've been around a month after Makeb was released. By this point you could expect most people in the group finder to know the tactics but me and my friend still asked at the start of the flashpoint whether everyone had done this before. We get a yes from the commando DPS but the guardian tank said nothing before pulling the first mobs. Needless to say, we took that as a yes.
Now, after having trouble healing the tank through the first few mob packs, I inspected his gear. Full basic gear with some Makeb greens and blues from leveling, not the best gear but managable, at least he'd bought some basic gear. I asked again whether he'd done the HM before and got the reply "Yeah, lots of times."
Then we get to the first boss. The tank died less than a minute into the fight, having used no defensive cooldowns and refused to get out of the red circles under the exploding droids. Now the droid turned to attack the tank and, surprise, he was easier to heal than the tank. We (eventually) managed to kill the boss and then had what was most likely the most amusing thing I've ever seen.
I asked the tank why the commando did a better job at tanking than him. No response. I then asked whether this was his first time in this HM and the response was "I'm in 66 gear, that's more than enough for this" before jumping into another pack of mobs without waiting for me (who was still typing) to catch up. As you'd imagine, he died and once again the commando tanked the pack until I arrived and started healing.
By this point, we were fed up of the tank and vote kicked him. While waiting for another tank we cleared some more mob packs with me complimenting the commando's tanking all the way. After getting a replacement we cleared the HM with no issue.
... After writing this I really feel like leveling a commando.
P.S. No I'm not getting commando and vanguard confused, in case anyone was thinking that.
Edit: I've just realised that this story proves the poster above correct.