On my server, there are always tons of people farming Steamwheedle, as well as off the coast of Hinterlands. Turtlescales are not for any specific type of LW, just the first mail you can make as one (along with the Scorpid items).
What I've found is that if you're a leveling LW, make the items from the mats and sell the mail. A little over cost for mats. Then, when they turn green, sell the mats on AH. Scorpid Scales sell much better on my server, but luckily you can get them both in the same place. Why I choose to farm TS is the side benefit of the Speckled Shell fragment, which drop at a unbelievable rate. A stack of 5 sell for around 45 silver, and with a merchant in the area, I can get easily 10g/hour as a 50+, plus have a few stacks of Turtlescale for AH fodder to boot. That is, of course dependant on others farming in the area.