So? A customer came into my work last week and bought 12 3DS's

Can we get the Troll Whisperer up in here. I think we have a problem.

There's a reason the 3D slider exists, so you can adjust the intensity of the effect to better suit you. If you have never played it before, playing it at full 3D will, of course, mess with your eyes. 

After having a 3DS for 4 months, I can play it at max 3D for long hours and not feel tired or sore in my eyes. About the ghosting effect, that's an unfortunate side effect of this technology, not just a 3DS problem. Some games mask that well though, I haven't seen any ghosting on MK7 or Starfox 3D, but on Zelda OoT 3D there was plenty of it. 

Buying? I read elsewhere they were a donation by Nintendo, it's a good marketing scheme.

You don’t know if Vita can do 3D? :O ….. It can’t not without glasses at least, there now you know.

The PSP 3 will though but that won’t be until about 6-7 years from now if the Vita sells well and at that time the 4DS will allow you to travel in time ;)

OT: the DS was used in schools so this is no surprise

Adjusting the 3D slider is key as you pointed out.  Also, I just wanted to add for Super Mario 3D Land you can push up and down on the d pad and it adjusts the 3D.  Not sure what the hell it adjusts but I found the default setting wasn't the best for my eyes and after viewing the other setting it seemed the 3D was even better.

yes, i think some of you do have serious problems.  sadly there is no one on here who can help you with those, you were just born that way.

If you leave the brightness at its default level (maximum), there will be lots of ghosting. But if you lower it to the middle, its almost invisible. Nintendo should have put the default level at the middle, I too was dissapointed when I first used it.

Hmm I've only kept mine at max setting.  I'll have to try a lower setting and see.  What exactly is ghosting?  Is it when you get out of the sweet spot and start seeing blurry images?

i dont see why i personally, or this museum would want to purchase 3dss where people cannot use them with the 3d slider maxed and recieve the full 3d effect(the idea of building up a tolerance to this is just absurd to me). additionally, the issue became far more problematic when moving so why in the world would this museum want these when people will most likely be glancing at the thing on the move.