There are surely practitioners of the stratagem on both political wings, and it’s the sort of ploy into which one can slip from time to time, but it seems to me that it is much more characteristic of liberals to weave rhetorical comforters that allow them to slip opinions through as objective fact. This, from Jamison Foser of the liberal Media Matters, is a fine sample. After 75% of a conspicuously benign essay on the need for substantive discussion of the healthcare legislation, this paragraph rolls across the table:

When you see people yelling, “Keep your government hands off my Medicare,” that’s a clear sign that the public needs some solid facts. How many people do you think know that health-care reform with a strong public option would cost taxpayers less than a plan without such an option? I bet that a distressingly large number of members of Congress don’t know that, and that very, very few voters do.

Thus, wrapped in a blanket of mutually agreeable observations about a heated debate, Foser slips through the talking point that really ought to be the object of his argument — because it’s a point that actually requires argument. Given the organization for which he writes, promulgating the assertion about costs probably is the objective of the piece, even though it’s offered in a tone of “for example.”
Ponder, for a moment, the not-so-fine distinction between error and misinformation. On the surface, here, Media Matters is requesting bias; in actuality, the group is endeavoring to insert it.