It’s interesting to see the change in PPPs’ polls since they became the official pollster for the Daily Kos.
In the Colorado Senate race, their most recent PPP poll has the Democrat leading by one point, while the more recent Rasmussen and Ispos polls have the Republican leading by 1 to 3 points.
In the Nevada Senate race, PPP has the Democrat up by 2 points while Rasmussen has the Republican up by 3 points and Mason-Dixon has the Republican leading by 2 points.
In the Pennsylvania Senate race, PPP has the Democrat up by one point while Quinnipiac has the Republican up by 2 points and Rasmussen has the Republican leading by 10 points in their most recent polls.
In the Missouri Senate race, PPP has the Republican up by 7 points while Opinion Research has him up 13 points and Rasmussen shows the Republican up by 9 points.
In the West Virginia Senate race, PPP has the Democrat up by 3 points, with Rasmussen showing the Republican up by 7 points and Opinion Research has the race as a tie.
In the Florida Governor’s race, PPP has the Democrat leading by 5 points while Rasmussen has the Republican up by 6 points and Opinion Research has the Republican leading by 3 points.
In the Pennsylvania Governor’s race, PPP has the Republican nominee leading by 2 points while Morning Call has the Republican leading by 11 points, Rasmussen shows a Republican lead of 14 points and Magellan Strategies has the Republican nominee up by 10 points.
Now, if you had asked me six months ago to rate the survey research organizations listed, I would have rated PPP better than Ispos, Quinnipiac, Morning Call or Magellan.
However, recently, PPP has pretty consistently leaned more favorable to the Democrats than other polls, or than it did six months ago.
I don't think you understand the difference between a house effect and inaccurate or "bad" polling. Just because you don't like the results of one firm's findings, it doesn't make them wrong. Yes, PPP has a house effect. So do all other polling firms.
What you don't address is longer term trends, which is probably a more accurate way of assessing pollster accuracy. If PPP were to find trends completely different from every other pollster, that means one of two things. Either they are catching on to something and everybody else is wildly off, or vice versa. If they are showing the same trends as other pollsters, albeit with a house effect (or, as Mr. Silver puts it, "systematic differences in the the way that a particular pollster's surveys tend to lean toward one or the other party's candidates"), that doesn't indicate bad polling.
http://www.pollster.com/blogs/how_pollsters_affect_poll_resu.php?nr=1
