Good art and bad art

While in class one day I heard my professor mention that a piece was bad art. Unfortunately I was not paying attention however it got me to thinking if there was such a think as good art and bad art. Since Duchamp's "Fountain" I don't think anything can be considered either good art or bad art. Even before Duchamp I don't think there was any bad art, even though at the time there were many pieces considered bad art. I think the idea of good art and bad art is more a judgment on whether or not a piece follows a particular style or genre. The fact is that since art can be anything and that the purpose of art is to draw forth something from its viewer then nothing can be considered bad art. If someone does not like a piece of art and considers it bad becasue of their dislike for it then the piece still achieves the goal of art is to bring forth an emotion or thought from its viewer. In the same sense becasue every piece of art draws forth some emotion or idea from its viewer then no one piece can be considered better then another so there is no such thing as good art. However, it is possible to say that a piece of art fails to meet the criteria of a style of art. In that case the art isn't so much as bad but unsuccessful in achieving what it was intended to achieve. However some of the best art to have ever come forth was deemed unsuccessful. I think the success of a work of art also has to do with the time it was introduced and viewed. For example there was a time when impasto was considered the material of the masters and oil based paints were for novices only. However now days many people believe that some of the best work ever produced was done so with oil paints. So when looking back through the history of art there really is no good or bad art but just art that was to early for its time.