Weight may not be as controversial in dogs as in humans but it is very important. Dogs have a good weight; a weight where they are healthy and able to do what a dog should be able to do. That is to run and enjoy life without the risk of injuring themselves. This discussion is strictly about dogs; so let's not be pointing any fingers k?
Pretty much if your dog is fat; it's your fault. Our dogs do not have the capability of feeding themselves nor controlling what and how much they eat. It is our job as canine guardian. I for one have always kept my dogs on the lean side. They are very active and excess weight can and does damage joints which will in turn cause health problems down the road.
The way that I tell if my dogs are a good weight is in the ribs. You should be able to feel your dogs ribs; ribs that feel like they have a thin layer of neoprene on them. They should have a waistline when you look down at them; even the bulky breeds have a waistline. Now some of the bulky breeds like Bulldogs, rotties, and mastiffs carry extra weight. But that is no excuse or license to be fat. All these breeds should have the same right to be able to run and have fun.
Seeing a fat dog is sad; they cannot enjoy life to the fullest and they suffer from health issues. Just recently I had my boy Luke at the vet; he's a skinny. He has always been a skinny type dog; he is very picky and it is alot of work keeping him even at this skinny size. So I took him to the vet to have another blood panel done just to be sure it is just Luke and nothing else to worry about. The good news is that he is just a skinny guy.
Keeping your dog fit includes exercise and what they eat. Always choose the best dog food you can purchase; or if you want to go the really healthy route; start cooking or feeding your dog a raw food diet. You know the saying "you are what you eat?" That applies to all creatures; at least those who eat. ;)