For those that may be new to the internet and WoW, or those that just simply don't quite understand, I'm going to list some of the basics for you. If you follow these suggestions then not only will the guild benefit from a friendly userbase, but you'll find yourself at eas with PUGs that you will inevitably have to join at some point, and generally make you a more sociable person both in game and out.
1. Don't get angry.
Ok, so the resto druid said he was feral and could tank when in fact he knows next to nothing about threat and couldn't tank his way out of a wet paper bag. Getting angry helps noone, and may cause a party to dissolve. Keep your head steady and show that you are the better player by carrying the party through even the worst situations.
Feel free to bitch about them afterwards though. We have the wall of shame forum for a reason.
2. Don't use text speak.
if u spk lke ths cuz it savs time, or you add numbers to words because you think it makes you look h4xxor, you'll find I have a short fuse, like many people, for the bastardisation of language. You don't have to be hemmingway, you don't even need to use punctuation all that often but for crissakes write the word!
3. Don't ninja.
Fairly self explanatory, if you do this often don't expect to stick around. this includes rolling need for AH, Vendoring, Alts and so on.
These are the three things that right away tell me if a PUG group is going to be succesful or not. follow them and you'll find yourself with plenty of friends in WoW, and you'll be more accepted in any guild you join.