Nintendo 3DS cognoscenti have known for some time that there are two types of displays you can get — IPS, the preferred one; or TN, the lesser — and it is a crapshoot what you get with each model of the handheld.
There is no way to tell by the packaging. Hell, in some cases, you need an app to tell what you have. And it's not uniform to the model line (3DS, 3DS XL, New Nintendo 3DS, etc.). The numerous bundles and design variants the 3DS pumps out each year can all have variable displays.
YouTuber Erica Griffin has acquired seven (7) Nintendo 3DSes in her quest for the unicorn of Nintendo 3DS gaming: a unit with IPS displays for both top and bottom screen, that doesn't have any dead pixels or shit under the screen and does have the same color temperature display.
I realize that sounds like the handheld gaming equivalent of watching a gluten-free vegan with a peanut allergy order at a restaurant, but she has a point about both the lack of quality control, lack of uniform specifications, and lack of transparency to the consumer. Those things reasonably matter to many people.
So, what's the verdict? The Hyrule Gold edition of the Nintendo 3DS, sold only through GameStop ($199, unavailable online), has dual IPS screens. The one Griffin ordered from a reseller, though, had defects under the middle of the main screen.
I have to confess, I looked at my 3DS XL, and while I understand the difference in contrast when you hold the screen at an angle, I could not see any debris under the screen. And I'm the kind of person constantly wiping my Retina displays because Apple seems hellbent for calling out and shunning the slightest aesthetic imperfection, both as a performance feature and a corporate value.
Her best bet now is the New Galaxy Style of the New Nintendo 3DS XL, which she happened across at a Fred Meyer (it's like Walmart, except for Portland). Again, there was a bunch of shit underneath the top screen (possibly a refurb?). However, Nintendo will replace a screen that has debris underneath it, if it's under warranty and the buyer sends it in and is willing to wait for a repair, yada yada. We'll see if this finally ends the quest for her.
I don't begrudge anyone their hobby or their collection (though I reserve that right for my brother, who incidentally is a gluten-free vegan). As a teenager I had ziploc bags full of bubblegum saved from wax packs of Topps cards (back when bubblegum cards actually included bubblegum, how about that. Now get off my lawn!)
But, in the kindest way possible, I might offer this advice to Griffin on her quest for her Holy Grail: