The "server" you are ssh'ing into is setup for it.
I just went over this on the Debian mailing list.
[link|http://lists.debian.org/debian-user/2007/03/msg05176.html|Re: problems with accessing X apps with ssh]
Following the suggestions about configs will help you get the auto-magic display offset and make it so you do not have to do the -X (and you can force -C there as well)
Cheers.
The guy was having an issue understanding "X", so I 'splained it to him.
edit: sheesh, I can't even finish three things at one.