When you walk in someone's home that is usually the first thing that you see, on their wall or sitting on their table and you know not to mess with it automatically, it's just a rich look that it has, like some one really took their time to really make, it and put time and effort into the art work.
Art is very subjective, and visual perception varies from person to person. One person might see a piece as amazing while someone might despise it. However, valuable pieces are virtually unrecognizable by the general public. Art experts can recognize valuable arts by its characteristics and signature, but regular people are unable to. A typical person could pass by a Van gogh at a yard sale and not even flinch.
There are so many different pieces of art that the common person probably does not know what pieces are rare or not, I think many people who have great trouble identifying a valuable work of art unless it was something that was so well known that everyone could get it.
When I walk into a person's house and they have artwork, I do always notice it. And I do always look at the different pieces and decide which one I like most. But I never ask who the painter is, and I never have any idea of who is famous or otherwise.