Certain channels can become filled with spam.
On every server I have been on I normally put /World in a new Tabbed chat window. On this server, I can see the channel when i talk, but if anyone else replies in it, I can't.
If I use chat in the first tabbed window I can see other talking, but not when in a different tabed window. This is consistent with whispers (I made a window just for whispers as well) as well as Global Chat channels. (Gen, Trade, LFG, etc) Unless they are in the primary window, i can not see them.
This can be really irritating considering either I /leave the channel when it gets to spammy, or Deal with the massive spam on my screen instead of having it tabbed in another chat window.
I can post my current chat settings (from the txt file) if you like.