When it's proposed by Paul Ryan (R-WI)!
Just like Republicans opposing President Obama's (ill-advised) tax holiday, Democrats in Washington are playing against type on Paul Ryan's revised Medicare plan. The cuts he's proposing come from means-testing the program, so that wealthier families get less from the government. The poor would be unaffected. But hey, it's a Republican idea, so it must be wrong.
Update: But Dana Milbank makes Ryan's plan sound so evil! A key to reading opinion pieces: most writers won't outright lie, but they will use the fine print. So when Milbank wants to make Ryan's plan look Scroogelike, he compares it not to current law, but to President Obama's budget-election document, which even the President never intends to make into law. Milbank's trope about tax cuts for the very rich refers to the fact that Ryan's budget would make the Bush tax cuts permanent instead of allowing them to expire. One may certainly disagree with this idea, but Milbank wants it to sound like Ryan is proposing tax cuts relative to current conditions.