The polls I see show a general dissatisfaction with the Republicans, and a large distrust of Congress in general. Haven't seen much that credibly indicated that people wanted the Democrats in charge.
If the Democrats continue to run on the platform where they're supposed to be better than Republicans, but still don't have a message or agenda that clicks with the average American, the Democrats are going to be surprised at how many of their traditional votes are going to go to independents and conservatives.
To a lot of moderate voters - a clear message and agenda is preferable to a candidate who insists first that they have plan, and secondly that the other guys don't, without any credible evidence to either... which describes the Democrats to the "t".
Congressional polls are useless, a broad base poll of vote intentions in Congress does not have any meaning of who will control Congress, where it is seat by seat based.
Dems usually do well in polls about voting intentions for the House, but actually have lost seats to Republicans in the elections, the incumbency is a strong factor in Congress elections.