Since using these goggles, I have seen approximately a 10% improvement in nodes. Let me rephrase that....10% more Herbs....And also, they are kinda sexy (FYI- supposedly, you do not have to wear them to get the 'buff', but why wouldn't you when they look this good!?)
In nearly two hours of straight farming on my gatherer toon, I saw only one, yes one, extra Ore node.
Compare that to 32 extra nodes of herbs. At the current prices of Mist Piercing Goggles on the AH, I figure that my tiny investment of 420g (lol'd at that price....) was paid for in the first 15 minutes.
The nodes are easy to spot as 'freebies' using these goggles....they appear as a Misty (hence the name) cloud around the plant/rock. Comparing to gathering statistics, I do not see they are necessarily 'new' locations, they just allow quicker spawnrates in an area. Extra is good, right?!
Kun-Lai Summit near the rare mob Korda Torros to getcha a pair of Forager's Gloves to speed up your picking/mining as well! It's only a 10'ish percent droprate, but hey, who's counting right?!
It's too bad you cannot get the Forager's Gloves off the AH like the Mist Piercing Goggles, but with your luck, of course they will drop!