Firstly, just because you're good doesn't mean the mud's made for you, yes good guys are generally the heroes of most stories but the bad guys on the mud wanna have their own stories, it's your job to be their antagonists as much as they're yours.
OOC respect is also important, when an evil player makes an event or whatever they're not generally doing it so someone can stop it, people trying to stop it is of course creates very interesting conflict but don't get all uppity if a bad guy tries too hard to win, again they don't exist to just be foils for the good characters.
NPCs are people too, this is actually for both sides of the conflict but it gets just silly seeing how many people go out and level, in a good person's case say slaying vampires and demons, but never tries to kill player vampires and demons. ICly they're all the same, similarly for vampires who'll go out and kill and feed off anything they find, unless they know it's a player. Yes eventually your RP with that person will establish they're different, for instance they get away when you try to kill them and might talk to you in the bronze, which can after a while separate them somewhat in your mind, but that certainly wouldn't occur when you first meet them and for a lot of people how sociable someone is doesn't have much bearing on if they should die or not.
No-one cares if you kill lots of NPCs, really, you're just levelling, ICly this'll often be taken as training etc, and there's certainly a fairly solid argument that slaying of everyday vampires has no long term benefit since they just sire new ones. Bragging that you're a big hero cause you level a lot is just kinda silly, the things people will ultimately respect are killing big bads(players), stopping evil plots and rescuing people, cause they're things that you're actually risking yourself, your life in a showdown and injuries or hospital time otherwise not for any exp reward or anything but cause of your character's will to help.
Nice isn't good, we're on a hellmouth, the epicentre of the battle between good and evil, there are war heroes on both sides, but that's what they are, war heroes aren't remembered for their kind and giving spirit. Characters who're just nice to evil guys aren't doing any good not to mention almost always succumbing to the previous point of treating players different to NPCs. This really comes from the slightly deluded commonly held western belief that an evil action is worse than an evil inaction. No idea why anybody thinks that, but they do, so not trying to kill/stop and evil person who you're fairly sure will go on to kill and hurt others is considered ok, but killing or hurting others yourself isn't. In both situations you knowingly choose a path with full awareness of it's consequences, the victim certainly doesn't care who kills/hurts them, but bizarrely one is seen as 'better' than the other.
This particularly ties into Nice v Good since the quintessential nice player will argue that they're better than the war hero types cause they don't kill, ergo the fact that they personally do not commit that small evil and allow a much greater evil are better than the ones who commit small evils and prevent greater evils, all done by refusing any responsibility for anything they didn't do directly.
I'm not suggesting that characters should break down in self-recrimination and tears every time they spend a minute not killing evil stuff, but it should be understood to be not as good as it could be. One thing that has irritated me in the past is characters esteemed as the epitome of goodness and heroism because they were nice to everyone, they never PK'd or RK'd or tried to stop events.
It doesn't make you more of a hero to have suffered more, god help me I'm so tired of seeing characters with horribly traumatic backgrounds or characters who seek out people to torture them and give them sob stories. I've honestly even seen two people arguing about who's childhood was more miserable, the idea being whoever had suffered more would be free from judgement by the other but allowed to judge them all they want. It's just stupid, if someone dies cause you screwed up they don't really care how much you cry about it, if you hurt someone they're just as hurt if you had a bad childhood as if you had a great one.
It doesn't make you evil to talk with evil people, on the contrary these can be some of the more interesting conversations and allow you to find out clues about what they're up to, the whole conversation can become a kind of verbal battle to find out info about the other's plans making for very interesting RP. Good guys who either segregate from the evil or just throw insults at it aren't any 'goodera' than others, and generally less effective.
In the end the take home point is, good needs evil and evil needs good, otherwise we'd all be bored to tears, so be their enemy, but preferably in a way that's somewhat respectful and they'd OOCly somewhat enjoy or find interesting.
Obviously everyone can RP their character how they want and a lot of people don't want to try to play the big hero or villain which is cool, but honestly I wish more people would, it's hard and filled with setbacks and things going wrong, but it'll always be interesting and challenging, you drive the RP along and you learn a lot by it. Sitting back may be safe but it's kinda boring too.