Depends on the seller. The one i bought from would replace it (for free) if there was more than 1 dead pixel in the middle, or 5 anywhere else. Most also offer an option to guarantee none for a bit more ($30-50 i think at the time, but dead pixels weren't that common, so i didn't bother).
Also, they DO have a warranty, but since you'd have to pay shipping, and probably get someone who speaks korean to translate for you, it may not be worth the hassle.
Also, they DO have a warranty, but since you'd have to pay shipping, and probably get someone who speaks korean to translate for you, it may not be worth the hassle.