Getting random drops always involves a bit of luck. In a PUG, not only do you need to have what you want drop, but you have to manage to win a /roll as well. In guild groups, you have to have DKP or whatever currency your guild uses for a loot system. Gear for the most part comes from time; eventually, you get the loot you need, but getting these random drops becomes far worse when farming for low drop-rate items such as pets and mounts. Baron runs, heroic MgT runs, Anzu runs, ZG trying to farm the various whelp and raptor pets ... some of us spend hours or days or weeks, and still never see it.
I have been on a pretty major achievement kick since prior to the Cataclysm launch, topping off old reps, farming pets and mounts, doing fishing achievements, all the things that take a back burner to leveling and new instances and raids. Trouble is, I have awful luck. Being a druid, I have run Anzu so many times I lost count and have never seen the mount; same with Baron, ZG and heroic MgT. No mounts from any of these places in hundreds of attempts. On the other hand, I have a guildie who has both ZG mounts, both Brewfest mounts, the Horseman's Reins, Anzu, and Rivendare's Deathcharger. He even got two of the raptor pets from ZG the same week he got the mount.
How lucky are you when it comes to farming rare drops? Have you been able to go in and get the drops in a few attempts, or have you given up in frustration, cursing the WoW gods?