I'm surprised to see so many people saying they dislike labs and golden retrievers. I wonder if it's because these breeds are somewhat the de facto "American dog" stereotype, and some people prefer to be somewhat against the mainstream.
I think one of the biggest things has already been mentioned; because they are so popular, every schmo on the street is breeding them, so you get a lot of really badly bred ones. My friends and I refer to them as "mock labs" and "mock goldens". They are very distinctive looking and acting - lighter in build, narrow heads, very barky, very high strung. When 40% of what you see in a breed is the worst of it's kind, it can be hard to remember the good ones.
For me, even most of the nicely bred ones are very pushy with their bodies, very in-your-face, panting dogs; all traits that many people clearly either like or don't mind. I'm pretty protective of my personal space, so it doesn't work for me. Obviously they have some great traits - there is a reason they are so popular!