Feral Heart

I'm going to get straight to the point.

Here's what I think it should and shouldn't be used for:

Brief conversations. This is not to say stop chatting in general altogether. I think it's ok if you want to use General chat to ask questions to those who are listening, or to try to find the location of someone. Little things like this.
If you want to continue your conversation, find that user and then continue in the Local chat.
Dragging out a longwinded sob story about how your life sucks/how you can't get out of that rock/what you did today/what your dog is doing right now in my opinion isn't what General Chat should be used for.
Although on the other hand, sometimes you get caught up in something and it just gets carried out.

Advertising Roleplay. I believe this is ok also, since how else would you gather others to join you in a rp ingame? However there is a fine line between Advertising and spam I think. If you post a few times with a bit of time inbetween post it's ok, however if it's all in caps every second, it's not ok and I think it's spam.
Mate/pup/cub/family beggars also has a similar scenario to what I just explained, and I'd be just repeating myself.
I should also be noted that users should know when to stop advertising/asking. If no one responds, no one is interested. Don't continue to press on with it and maybe try again in half an hour/an hour or so.

Roleplay. No. Just no. Because some/most users do not want to know how your wolf howled at the moon, or how your lion mauled that giraffe. It just clogs up the chatbox. If you want to roleplay, stick to Local chat, Group chat or even your own map.

Vulgarities Ugh. This is a huge no. I don't want to get into what I've seen that's been said over the General chat. ranging from sexual things/rape to other gross TMI bodily functions. I'd rather not hear about something like that so publically. Once again, if you really must talk about your TMIs stick to whispers and group chats.

Arguments. If something comes up and causes a fight, don't slather it all over General Chat. No one wants to hear your swears, crude/petty remarks and all round rage at one another. This also just unpleasantly clogs the chatbox and should be taken into local or just take your argument out of the game and have it over email/PM/MSN/etc.

Bullying. Another huge no. I've seen on multiple occassions small handfuls of users pick on another player for various reasons. I guess this could also come under Trolling aswell.

And finally the big ones, Spam and Trolling.
No no no no no no no. No.
I don't think I really have to explain this one. I'm pretty sure everyone has seen their fair share of spam and trolling in it's various shapes and forms in the General Chat.