When ever talking with a liberal and they say that vague stuff I immediately ask for specifics. It stumps them. They just hear this crap over and over and begin repeating it without knowing any details. When the say the Republicans ruined America for the past 8 years I ask how exactly? They stumble and then mumble something about deficits and I remind them the last Republican Congress fiscal budget was 2007 and only had a $160 billion deficit while Obama is running up close to a $2 trillion deficit his first year.
Just always ask them to be specific and you can rip them a new one.
That's one approach. Here's another.