It's against the rules to swear at another person, but it is not against the rules to swear at nothing in particular in moderation.
thats why i said It would also lower the number of bans and complaints against people saying inappropriate words.
It is impossible to do is the problem. Here is a just a short list of the numbers of ways I can type "crap". crap, c*ap, cr*p, cra*, c rap, cr ap, cra p, c rap, cr ap, cra p, c-rap, cr-ap, cra-p, crappy, Crap, cRap, CrAp, CraP. While I wish too the people didn't say words like the f-bomb (my little siblings watch me a lot.) People will always find new ways to swear if they want.
Easy to fix with the spelling There is a tag in bukkit called EqualsIgnoreCase Can be used for commands and chat
Even though there's absolutely no use in doing this because the rule will not change in the foreseeable future. There is no problem with occasional cursing and the fact of the matter is that if you're on the internet, you accept the fact that there will be cursing. Cursing is only bad in the minds of those who were taught that it was bad. As far as i'm concerned, its nothing more than a form of expressing one's anger. Sure, one could use something less... archaic, but its a way of expressing your anger. There's no reason to censor such.