Why do Republicans have more leeway to attack Democratic states/cities than vise-versa?

[Chancellor Tanterterg]

I actually don’t think they do that nearly as much as they did in, say, 2004.  “Hollywood liberal” and “New York values” have always been dog whistles best understood as a way of saying “my opponent is a dirty Jew” and/or “a pawn of their Jewish masters.”  For this reason, as explicit, unapologetic anti-Semitism went mainstream in the Republican Party, such dog-whistling.  

It’s like how when Republicans rant and rave about violent crime in places like NYC, Chicago, etc, what they really mean is “grab your guns because the n*gg**s are coming to rape your women and steal your money!”  If it ever becomes mainstream in Republican politics to just go around using the n-word and/or get that explicit, they’ll drop the dog whistle and just start saying what they really mean.  And they’ve been getting a lot more explicit since Trump got elected in 2016 (not that they were ever particularly subtle).

“San Francisco liberal” meant a Republican was saying someone supported the “homosexual agenda,”  but now gay rights isn’t as good an issue for Republicans to run on and the Republicans who still care about it generally prefer Republicans to be as explicit as possible when tossing homophobic red meat to the mob.  As such, using the term has become increasingly unnecessary for Republican politicians.

The Democrats definitely have their own version of this, specifically making fun of the south.  However, neither of these really play to a deep-seated, grievance-fueled bigotry the way Republican geographic attacks did for the Republican base.  As such, it was never really useful for Democratic politicians the way it was for Republican politicians.  Not that Democratic politicians don’t engage in other forms of dog whistle grievance-pandering, but geographic attacks aren’t usually one of those.