If it fails (badly) in multiple cases and is only good for a very general snapshot then yes that is hugely inaccurate. I can point a cheap camera at a forest and that is fine for a blurry image of 1000 trees but if someone asked me if it was an accurate tool to examine an individual tree Id say no.
I'm no body builder though I do go to the gym, always been large framed big boned and when I was a healthy BMI I was constantly accused of being anorexic. That would be even worse these days considering I have a bit more muscle mass.