It is fakeable, but transparently so. Being bound to technology (as the critics will always point out to us) art photography can rarely keep secrets about process (note Cory Wright's website info) and the Gursky manipulation 'scandal' with the Rhine image was a prime example of people getting up in arms about this stuff. Critics have a hard time accepting photography that isn't anything but completely authentic - technically and subjectively, today more than ever I think. Film effects are almost solely an amateur phenomenon, from what I've seen. Instagram has made it a real problem for any serious art photographer to even try this now also. The American landscape photographer Michael Fatali always made a point of letting his viewers know there wasn't any technical trickery - he knew his wider credibility in the art world depended on it.
I think Flickr is pretty close to being a complete vacuum, with it's own trends in representation and aesthetic, but there's definitely that outside influence from the 'proper' art photography world. I've often seen streams and sets from photographers not even hiding the fact they are ripping off a big name artist - they know they can almost get away with it. Not when I'm around however
As a side note, I think Flickr is largely made up of people who pick things up - concepts I mean - without knowing and there is a massive amount of creative naivety and general ignorance about the lineage and history of art photography. I've been scared away from it because it's a world unto itself and it influenced my 'visual vocabulary' in a way that made me uncomfortable, stunting my growth. Sitting down and really assessing my images one night, this was almost a grand awakening. But you do see hints at ideas and visual styles, unconsciously appropriated perhaps, from the 'real' world of contemporary photography and classical work. It does get filtered through, but very rapidly recycled into superficialities.
Its interesting to read others views on Flickr. I see Flickr as a constant source of inspiration - of finding things that interest me and things that I think I might like to try. Is it copying? If we didn't copy we don't learn. And if that is theft, the only true photographers out there must be blind.