1) If you're going to insist a pairing is out-and-out canon, or has more canonical support than other pairings with the same characters, you had better be prepared to put your money where your mouth is.
- You'd be smarter to avoid insisting anything's canon unless the creators themselves have them actually saying those Three Small Words and getting married.
2) If someone has a pairing they like that you don't agree with, your options are to either STUF or offer polite debate playing devil's advocate, particularly if you don't feel they did as good a job as they might have been able to do in presenting their case for the pairing. Right way: "That's an interesting take you have. But how to do you explain _______?" Wrong way: "What are you smoking? There's no way that pairing can work!" Constructive debate designed to foster calm discussion and analysis is good. Attacks and flames and heated arguments are wanky. There's nothing wrong with getting people to think about why they like a pairing, and nothing wrong with listening with an open mind about other pairing choices. Ignore the rabid fanpoodles. Liking and/or acknowledging more than one pairing for a character does not make you a traitor worthy of being stoned to death. It makes you mature.
3) If you cannot defend a pairing without bashing another character, especially if the other character IS canonically married to or otherwise clearly with another character, don't even bother. You can like any pairing just fine as a pet pairing, so long as it's not insisted that it is canon. (the community founder's own pet pairing is Dynast/Dolphin in the Slayers -- she like the pairing, but acknowledges it has no basis, she doesn't pretend it's canon, she just likes it.)
4) This is not the place to bitch about pairings you hate, nor is it the place to rant about characters you dislike. It's the place to come when you're tired of pairings you do like -- canon or not, whether they be yuri, yaoi, or het -- getting ripped on by sucky rabid fanpoodles. Yes, there will be het supporters and yuri supporters and yaoi supporters among the ranks. Deal.
5) Leave Real Person pairings OUT of this. This cannot even constitute as canon. I'll allow that it has a fandom, but when people start arguing over which real, live person is sleeping with whom...the community founder lives in a small southern town. She hears enough of that on a daily basis. Stop acting like gossipy hair salon biddies. Keep it to fictional characters. This comm has enough potential wank fodder that it doesn't need this can of worms tossed into the mix.
6) No one is going to like and support every pairing. You will allow that other people have the right to their pairing preferences. If there's a pairing you particularly hate, constantly bringing it up wherever you can and harping on it will earn pointing and laughing. If you can't play nice in the sandbox, you are neither old enough nor mature enough to be allowed out without supervision.
7) And for the lov'a little fishies, people, this is NOT a "het vs. yuri vs. yaoi vs. slash vs. etc" wanktastic argument forum. Anyone who plays the "Yaoi/Het/Yuri/Slash/femmeslash/whathaveyou is icky and evil" card will find that it is open season on wankers, and the community mods are among the people who will be lining you up in their mental crosshairs. Don't say you weren't warned.
8) Act mature, type like you have some degree of intelligence, DO NOT use netspeak or fangirl Japanese, and don't encourage flamewars. Fandom_Wankers are present. Wank at your own risk.