Just my luck, right? Gone through 1 exchange already because my very first X had a speck inside one of the back camera lenses. My new one was perfect, except, in the evening while shopping, an even bigger speck appeared on the same lens, as if it was already there hiding, then, bam! I’m now awaiting to have it exchanged again tomorrow morning because the Apple Store didn’t have spares until then. I gotta give it to Apple customer service, though. They really treat you well and will take care of you. TLDR to updates: Gone through 5 phones in 2 days. All but the one I have right now had tiny specs of white dust on the rear bottom camera. Some only showing up after having the phone for about a little bit. I am crossing my fingers on the one I have right now which is so far dust free after about 2 hours or so. If you don't get a 4th update here, all is dandy! UPDATE 3: Got to the Apple Store and as usual, the team was more than happy to rectify the problem. I was brought another brand new unit, opened it up and checked it again...what the heck is happening?...this one has it too, and on the same bottom camera! Showed it to the sales associate, this time I was really disappointed. Then she saw it but she had to call a supervisor to verify since this brand new unit she just got for me was barely touched. Then the supervisor checked it himself but instead of agreeing, he kept saying he cannot see anything. This went on for about 15 minutes until he wouldn't want to do an exchange anymore, telling me that these specks of dust are to Apple's manufacturing standards...yada yada yada. I stood my ground and insisted on another exchange...the last one for me or I'll walk away without a phone. Then they agreed. Lo and behold, the last one didn't have specs, but knowing this might not be the ultimate ending to my story, I left the Apple Store anxious and nerve racked. So far, I got home after about an hour and no dust...fingers are still crossed. UPDATE 2: Well, what do you know, folks...another tiny speck showed up in the bottom rear camera again! I swear, I checked my replacement properly before I left the store and kept checking, walked around the mall a bit then checked it again after about 30 mins...and there it was. This proves that dust is definitely inside the modules ready for them to be shaken loose. It's disappointing indeed. Back to the Apple Store for another replacement. UPDATE 1: I got a perfect replacement finally. Now let’s see how this holds up and if it’s hiding another speck in there somehow.