The Washington Post gave us these results under the headline "Hillary Clinton's Image Continues To Decline". That seems to me to be just another example of Hillary-bashing, probably in an attempt to stir up controversy and increase readership. They could just as easily used the headline that I did, which tells us more about the poll -- that Clinton is still viewed more favorably than either of the two leading Republicans. She is viewed more favorably by 5 points over Jeb Bush, and by 6 points over Donald Trump (and her unfavorable rating is less than either of those two).
The results are from an ABC News / Washington Post Poll that was done between August 26th and 30th of a random national sample of 1,005 adults, and has a margin of error of 3.5 points.