Great post, Ryel. I must emphasise this:
Really. On these forums you may read very obnoxious opinions from very cocky raiders who're just condescending people, in and out of the game. But in my personal experience, in a variety of MMORPG's, the OP's mindset is how it goes most of the time. People, on average, are much nicer than you may think.
I'd be lying if I didn't admit that I had my fair share of bad experiences in FFXIV (sadly, the average level of jerkiness in this game is a bit higher than what I've seen in most other MMO's), but you know what? IGNORE them. You know what's better than lying your way in with jerks, for your own enjoyment? DON'T PLAY WITH THEM. They don't deserve you, they don't deserve your lies; be honest and find nice people, that's how a game is enjoyed.
I PUG a lot, in many games, just because I like that (and one's FC might not always be online or available), and I can tell you that most people are willing to give you a chance. Just be honest about it and listen carefully, and ask questions if there's something you didn't understand. And if you screw up a fight: it's OK, it's normal, we all need some time to fully 'get' how to do these fights. What we don't like, however, is when people lie about their experience, don't want to learn anything, and don't own their mistakes. We all make mistakes. Lying about them doesn't get you any closer to a good result, let alone making you appreciated by your team. And let's not even talk about possible friendship which, eventually, is probably the point of playing game together, isn't it? Having a nice time, having fun, getting to know nice people and everything? :)