Graffiti is something written on a wall, and, of course, art can be exhibited or produced anywhere: a wall is just another venue.
Matthew SlotoverDuchamp's urinal was art once he put it in a gallery. In fact, one working definition of art is anything that is in a gallery.
Matthew SlotoverArt is about the context in which it is made as much as the object itself; objects take on different meanings in different contexts. If the artist is unaware of the context, it's very unlikely the work will be very good.
Matthew SlotoverArt and society was a lot more subject to sexism 50 years ago than it is now. Since that period, there have been plenty of very good female painters, 2006 Turner Prize-winner Tomma Abts among them. How much history needs to pass before an artist is called 'great'? That is the real question.
Matthew Slotover