Look online or in the tabloid press and you'll find people berating people's fillers. Whether it's botched jobs, horror stories or just a healthy dose of bullying someone about their appearance. Holly Willoughby on This Morning several years ago turned her nose up and said, "I think you can tell when someone has had fillers, they look pillowy".
This is an example of a cognitive bias know as the Toupee Fallacy. If you said, "all toupees I've seen look bad, therefore they must all be bad" then you'd be doing he same thing. If somebody had a toupee and it looked good, you wouldn't know you were looking at a toupee. This is the same with fillers. If It's been done well and thoughtfully, you would just think the person looked beautiful.
So the answer is no, you can't always tell if someone's had treatment done. You're fooling yourself if you think you can. You can just tell when it's easy to spot.
