Use whoever's around, and keep shooting
Warhol went to Jack Smith's shoots, cast Smith as Dracula and borrowed his performers. He credited Smith with how he made films.
Flaming Creatures was made on a rooftop with friends in drag, out-of-date film and no script. Warhol was there for Smith's shoots around that time and filmed some of them.
In Batman Dracula Warhol shot and edited while Smith wrote the loose scenario, chose the costumes and played the vampire. Mario Montez, one of Smith's stars, went on to Warhol's films. In POPism Warhol wrote that he took from Smith the habit of using whoever was around and filming until the actors got bored. The two later fell out.
Acknowledged by Warhol in POPism