Obviously this is not to say that incumbents never lose. Nor am I saying that the poll results are not good for what they are worth. It's just that they aren't worth much.
In 2008, plenty of GOP incumbents were beaten, because voter were out to vote against anyone with an (R) after their name. This year, because of the hated 0bamcare, cap and trade, bailouts, record deficits, out of control spending etc, voters are even angrier against the Democrats than they were against the Republicans in 2008. Plus in 2008, Rasmussen had the Democrats ahead by 7 points in the generic congressional poll and the Democrats ended up beating the GOP by 79 seats in the House elections.
This year, not only is the GOP is ahead of the Democrats by 10% in the Rasmussen generic congressional poll by a massive 10%(bigger than the Democrats poll lead in 2008), but Republican voters are vastly more energized,angry and determined to vote than they were even in 1994, when the Democrats got clobbered but good.
The Democrats are going to get slaughtered in November. And you can quote me on that.