I've found it more difficult to make gold by auctioning recipes on Kirin Tor than I have on the other servers I've played on. Zul'jin in particular turned out to be very fertile; my highest level toon there is only 23 but in a few weeks I accumulated over 3500 gold. Proudmore gave returns at a similar rate.
I think this is because these servers have been around a long time, and their populations have matured. There are a lot of players with high level characters and a lot of gold, and when they level alts they don't mind paying good money for their profession recipes and patterns.
Velen, where I've played most, is newer (2007) so there is not as much gold floating around, and its active population is smaller, but it has still been fairly easy to farm gold through recipe reselling.
By contrast, Kirin Tor is an older server than Velen, but it's an RP server and its active population is noticeably lower than any of the other servers I've played, at least judging by auction house activity. I tried my strategy of buying (mostly cooking) recipes in remote areas and putting them on the AH. This strategy worked great on the other servers but hasn't worked as well on KT.
Part of the reason is that until yesterday I didn't farm recipes in as diverse locations on KT as I had on the other servers; I mostly bought recipes in Zangarmarsh, Hellfire Peninsula, and Terokkar Forest. Yesterday I went out to Nagrand and then toured Kalimdor and Stranglethorn, farming a much broader selection of recipes.
I'm already seeing good payback, with a lot more sales this morning than I've had in several weeks of auctioning only Outland recipes.