In my experience shyness has nothing to do with quality. Sure they need more work. Have seen plenty of "I own the world" kind of bulldogs getting beaten by what people consider a time wasting shy dog. I totally understand why people don't like shy dogs. It's not a trait I consider a good thing either. But some dogs are just born with low self esteem. I have had it, and mine were absolutely not neglected. Some blood are more known for it's shyness. It's just a bit more work with socialisation.