Hi Cabo,
One of the most common reasons for doggy odor is seborrhea... excessive skin oil production, building up slightly on the skin and eventually becoming rancid, with the associated doggy odor. Strong medicated baths may give a fleeting relief for a couple days, but it returns.
Sometimes it is obvious to the eye, but with as much water exposure he probably looks pretty clean.
Any other skin problems, like itching? This often accompanies seborrhea. And, being Lab and Golden mix, I would wonder about his having some allergies, (hay fever type). Also, a low thyroid is also frequently associated with seborrhea, as are some nutritional deficiencies, like essential fatty acids or minerals that are usually supplied in plenty by standard dog foods.
Best evaluation will be done by your vet, who can put hands and eyes on the dog. I suspect the problem is simpler than you think. Best wishes.
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