Yeah, cameras calibrate out those pixels essentially by taking a photo of total darkness (taking an exposure while the shutter is closed) and discarding any pixels that still read bright. I noticed this happen a while back and the location of the dead pixel was visible if I took a photo of fabric. I could see where the pixel was being interpolated from surrounding pixels. Super subtle, I could only notice by knowing a-priori where the dead pixel was, but something that an algorithm could detect.

I wonder how well this fingerprinting technique works when photos are resized or manipulated, though.