Mesmers are not very good farmers, so it is hard to find good places for them. One good place to farm with them is outside Elona Reach; there are three wreckages in quick succesion.
The first thing you need to do is fix your mesmer up. I use this build to farm this place (runes not calculated):
Fast Casting: 7
Illusion: 10
Domination:7
Inspiration: 9
The skills I use are: Backfire, Mantra of Persistence; Shatter Delusions, Conjure Phantasm, Phantom Pain, Illusion of Haste, Ethereal Burden, and Ether Feast.
Whenever you see a drake alone, you can take them down easily. First cast mantra of persistence before you enter battle. Then cast Phantasm, Phanotm pain, and Backfire. If the drake is not dead yet, use Shatter Delusions.
If two drakes are by you, though, it is best to just run around them using Illusion of Haste. Be sure not to aggro them, though, as they can still catch up to you.
Now, for the farming. Follow the map to Wreckage A. Press Alt when you are around there to find the wreckage. Then let your char die by either the drakes or the scarabs; you should be ressurected at the res point (Note:if you are standing on the top of the ridge, you will not ressed at the res point. Make sure you go around to the bottom of the ridge).
When you are ressed, go right and hug the canyon wall for about 10-15 seconds. You should see Wreckage B (hold Alt). The, keep on following the wall right for another 10-15 seconds to find Wreckage C(press Alt).
Wreckages A and B give you items, while wreckages give you gold. Also, killing the Drakes will give you additional XP and items.
I make about 250 gold per run. Each run is approximately five-ten (depending on what you kill) minutes, so that is 1.5k-3k per hour. That may be shabby for a warrior farming, but it is pretty good for a class like a mesmer. It is the best farming spot of have found yet.
Edit: So how do you guys like it? I think it is the best spot for a mesmer to farm, because you can solo drakes if they are alone. Also, it does not take to long once you get the hang of it,.
As for illusion of Haste, if you have your illusion skill at the setting I recommended, by the time the spell wears off and you are crippled, it is recharged and you have your energy back. The only bad thing is you have to stop running to cast it.
Edit2: Well, guys, it looked like Arenanet nerfed the second part of my run

. I tried it again today many times and it looks like you cannot res back at that res point. Damn them. The first part of the run is still valid though, and so is the killing of the drakes. Killing the drakes actually makes you the most money, +120XP, because their drops are very good. With just the first part of the run, I still make around 150 gold in a shorter time. The highest I made doing this run today was 235 (with just the first part!)