I would guess it's easier to spot the amount of noise when you skim through all the submissions as opposed to peeking at the highest voted stories on the front page every once in a while.

The the posts that end up in the front page have been filtered, an unfiltered RSS feed has even the failed attempts to get easy points.

It appears to be easier to get into the RSS feed than the front page, so if you follow RSS you see many truly terrible submissions.