Genre satire is different than political satire in that most people who make it often do so out of love for the genre not hated. In fact these works of media aren't nearly as funny if you aren't familiar with the tropes and story beats within a genre, so the audience also ends up being fans. The people who watch slasher parodies are the same people who enjoy slashers.

I like Dead Men Don't Wear Plaid, a farcical noir film that is like a quilt made from the footage of a bunch of other films with original fabric connecting the pieces.