Do you ever look at someone (In real life at the movie or on television) and try to guess what is the artificial part on them. (Hair, nails, breast, teeth, etc)? I look at some people and try to see if I can tell they are wearing a hair piece, half false teeth, had breast enhancement etc.
I saw an episode on discovery on plastic surgery and this guy had calf inlants to make his chicken legs look better and another dude had a fake 6 pack to look better.
Porn blooper, "oh my god cut cut cut, you bastard you broke my ass, damn it I paid $25k for that ass and you had to shove into it so damn hard your gonna pay for this. I want that tape you all saw it, my ass is broken will somebody get the duct tape so atleast I can stop bending over and actually sit down.
I dunno, I just can. I can tell if it doesn't look like a real hair color or if it doesn't match the rest of them. And teeth, if you're talking about those porcelain thingies, they just look TOO perfect. I dunno, I'm sure I'm not accurate all the time, but I have found that I notice things like that more than my friends do. I don't really do it consciously or anything, either. I just happen to notice.