The definition of Grindhouse:
A theatre playing back-to-back films exploting sex, violence, and other extreme subject matter.
Grindhouses were typically a dirty old thearte who would play gorey movies. These movies often only had one copy so they would become dirty and cut-up therefore makign the movie kind of shitty.
The makers of grindhouse sort of simulated this type of movie.
The first one called "Deathproof" is absolutly amazing. It's probably one of my favourite movies of the year
I suggest watching it