Yes I totally am in agreement with what you are saying Tinyplanets, and in reality it is not easy to define obesity in humans, and dare I say..... it often consistently seems even harder to define obesity in dogs.
Obviously there are useful breed weight charts, picture guidelines and written text to help, yet up till now I'm aware of quite a number of dogs which have been wrongly classed as obese - with 'excess' neck and 'excess' around the spine/tail area - and these dogs were later classed as not obese because the muscle groups (Trapezius and Gluteals) were highly pronounced. Dogs with full lateral thighs (which are where the extremely strong biceps muscles are) can also be wrongly classed as obese, particularly when the dog is in full coat!
The hands-on approach can be a useful way of feeling your way along a dog to decide whether a dog feels overweight, though unless the same person is used for all dogs, the individual conclusions of obesity are bound to be contradictory.
Might I add that when a label is given to a dog ("obese" for example) there are connotations, and in this case the inference is unfortunately (current and/or) future ill health. So it is important that this label is used accurately.