I recently had a woman bring me what looked like a Labradoodle. She'd had the DNA test done and it came back Poodle, GSD, Irish Wolfhound, Golden Retriever, and some kind of Terrier.
She was convinced the test was accurate and even told me how the dog's physical and behavioral traits could be traced to each breed. "That's the Terrier in him", she'd say when I remarked about the coarse wiry hairs in his coat, and "that's the Retriever in him" when I talked about the soft cottony hairs in his coat.
Here's the dog... his matting was so extensive that I had to peel it off little by little with the clippers, and it came off in one big piece. The owner was clueless about that, too.