William Earl “Ishtar.” “From Justin to Kelly.” “Beverly Hills Chihuahua.” “Cats.” No, this isn’t the marquee of a movie theater in Hell, but rather some of the episodes of bad movie podcast “The Flop House.” For 16 years, Dan McCoy, Stuart Wellington and Elliott Kalan have analyzed box office or critical bombs that either failed to make a dent in pop culture or became notoriously reviled. “The Flop House” is hitting a milestone on July 15, with the group releasing its 400th episode, a discussion of legendary bad movie “Troll 2.” What started as a lark in the early days of podcasting has turned into a refuge for the trio’s creativity, friendship and even a way for the hosts to pay the bills.