Fear-mongering tactics on the left are no better than fear-mongering tactics on the right. You might disagree with U.S. Rep. Paul Ryan's budget proposal, but creating an ad that depicts Republicans shoving grandma off a cliff is a bad move for several reasons.
1) Claiming your opponent actually wants to kill U.S. citizens is just a tiny bit extreme. Paul Ryan is trying to balance a budget. He's not a closeted murderer. Ryan's proposed budget does cut Medicare spending significantly, yes, but so does President Barack Obama's heath care law (dubbed "Obamacare" by opponents).