This may also be used to refer to metal bands that are just trash in the sense that they should be thrown into the trash can.
Person B: "Well, I wouldn't really call them trash..."
Person A: "No, that's their genre. Trash Metal."
Person B: "Oh, you mean Thrash Metal."
Bands such as Linkin Park, Slipknot, and Korn who are labeled as influential artists and are highly full of themselves, are indeed Trash Metal.
Ironically, artists actually influential to the metal scene such as Metallica, Megadeth, Slayer, Exodus and Exhorder are often dismissed as pure fanboy garbage and are labeled as Trash Metal by many nu-metal and alt-metal lovers.
Man, whoever says Exhorder is Trash Metal are complete dipshits.