Look around . . . there is bad photography being used everywhere.  And it's not just on billboards and web sites, I've even seen pixelated pictures published in magazines.  To steal a line from a TV commercial I saw last night, "People wouldn't know a good photograph if it sat on their lap and called them mama!"  (I think the TV commercial said people wouldn't know HDTV.)   I don't know if art buyers are ignorant or if they just don't care. 

redhat

I teach photography to high school students. Many students are perfectly happy handing in images where the focal point is blurry, the background is the school parking lot (ughhhhh), or the exposure/contrast is blah. They know they are going to get a poor grade but the low quality is not a big deal to them. These are our future consumers . They know the qualities of a good photo, but they are content with substandard photographs. I feel that low res internet images make them all to comfortable in accepting poor shots.