I don't know why my black labbie is smelling so bad lately. He is 9 and has a bit of arthritis so not as mobile as he used to be.
He is a swimmer. we are not in UK and he spends a good amount of time in the pool. But its not just wet dog smell, if he is lying in the kitchen you can smell him from up the other end of the house. If it was because of the chlorine surely this would be a usual summer thing as he has always swam a lot in summer. I know this sounds terrible, but it smells like something rotten 
I checked his ears, they seem ok and I don't think the smell is coming from there. Gave him a good bath yesterday, used the dog shampoo which usually makes him smell good (its got essential oils in it), but nope, still ponging today.
Apart from a bit of constipation a couple of weeks back (all seems fine now) he seems fine.
We have been having a really bad heatwave lately, so I am wondering if its sweat? Do dogs have smelly sweat??