There is absolutely no way to avoid drama. Thirty different people have thirty different opinions, priorities, play styles--the list goes on. Pleasing one person is going to piss off at least one other and vice-versa. Any guild that says they are drama-free is full of it and any person who says they're drama-free is lying. Some guilds handle drama better than others, just as some players do, but to say that either has neither is a flat-out fallacy.
Most of the drama I've experienced has dealt with loot and/or raiding. Now, the two tend to go hand-in-hand: when you raid you get loot and you need loot to better yourself to further your raiding. Most guilds handle loot drama through a priority system of some sort, usually combined with some sort of metric to balance the amount of effort someone has put out with the amount of gear they receive. No system is perfect, which accounts for the variety of them out there, but some handle certain situations better than others. Outside of guilds, you're at the mercy of the raid Master Looter.
I've been told that I'm far too optimistic--perhaps that is the case. When I walk into a PuG raid, I generally assume on-spec before off-spec, pass if you've already won something, be courteous, loot the stupid puppy so someone can skin him, and if something extremely rare drops everyone currently eligible for the item gets a roll. It seems that these rules, though common sense, don't apply to every raid. And, even when they do, it can still cause drama.
Alliance actually had Wintergrasp and a guildmate put together a VoA 25 run. We filled a number of the slots with mains and alts from our guild and PuGed the rest. The question was asked what the loot rules were and the response was "MS OS" (for those not used to the shorthand of lazy people, it implies that Main Specs have priority over Off Specs). The fight was ugly but we killed our boss on the second try. A rogue piece drops, a priest piece (too bad the only priest in the group dropped after the first wipe), and some leather PvP bracers. Only one rogue in the raid so he gets the rogue piece, then the bracers are rolled for. Now, I'd never really dealt with PvP gear drops before. They generally are not very good for PvE and the guild policy has been that all interested people can roll on PvP gear. The bracers are actually a best-in-slot item for the feral tanking kit I've been working on. The rogue has rolled a 95 and my chance of winning is slim, so I roll and get second highest at 68 or somesuch. The raid-leader states that since the rogue already won a piece, it's going to the next person and I now have a pair of leather PvP feral bracers in my inventory.
If I'd actually thought I'd win, I'd never have rolled; while guildies would understand (and many said that I deserved them), PuGs certainly would not. "But they're a healer?" was mentioned in raid chat right as I received a whisper from both the rogue and a feral cat druid who had been the third-highest /roll. As I'm receiving these tells, the decision is made to go kill another boss and as one of only 4 healers I'm racing off to keep the tank out of that laying-on-the-ground-motionless state.
Long story short, the rogue offers me gold for the bracers and the druid asks for them because feral is his main spec and then says it's 'really shitty of me' since I 'only have 1000 kills' for PvP. Considering I'd only started PvPing casually about a week before, I was pretty proud of those kills. That and I hadn't responded to either because I'm trying to keep people from dealing with more repair bills.
I could have said fsck them all and kept the bracers, saving me 45k honor that could have gone to my cloak instead. No, instead I did the noble thing and gave them away. Not to the rogue, since he'd already won an item, but to the druid after demanding an apology. I haven't been yelled at on the realm forums so I guess I did the right thing. I'll never /roll on PvP gear that isn't caster related outside of a guild-only run again.