Only 22 percent of voters think most members of Congress deserve re-election while 72 percent believe they do not. According to Gallup this puts it on pace to be the lowest ever for an election year since they have been polling the issue. From Gallup:
As has always been the case voters have a higher opinions of their own member of Congress with 50 percent thinking their own representative deserves reelection, but that number is also very low by historic standards. It is even lowering than it was during the wave election 2006 (54 percent) and the wave election of 2010 (51 percent).
Of course given the poor design of our election system, all but handful of seats are effectively predetermined and over 90 percent of incumbents are likely to win re-election. Which probably explains why our opinion of the Congress is so incredibly terrible. The chamber which is supposed to most closely reflect the people has been progressively made insulated from the will of the electorate. We are now at the point where Republicans can lose the popular vote this November by a wide margin and still win a majority of seats.
At some point we need to start acknowledging that the problem is less the individual people currently in Congress and more about how badly the current election rules are rigged.