When the Rush Limbaugh show started in 1988, many callers would express how much they loved the show. It took a lot of air time, so he asked them to just say "dittos" to agree with previous callers who like the show. It doesn't mean that they agree with everything he says. If you were one of his 30 million listeners you would know this.
I'm an admitted Rush Limbaugh Ditto Head because I like the show, not because I always agree with him.