This quote from Paul Celan, possibly the greatest European poet of the 20th century, made me think about the difference between art and advertising. Celan said:
For a poem is not timeless. Certainly it lays claim to infinity, it seeks to reach through time [durch sie hindurch] through it not above and beyond it.
However you do see people enjoying old adverts, say the one below for Guinness. This would never be released now, other than in an ironic way. It no longer sells, but has an art-like quality that manages to reach through time to us still.