On his second album, No Fences, country's hottest new ''hat act'' continues to display a wide streak of individuality. Garth Brooks offers the same mix asany other traditional country performer ballads, honky-tonk, and the occasional kick-'em-up rhythm tune but he usually finds off-the-wall ingredients to put in it, such as ''The Thunder Rolls,'' a cheatin' song cast in a Gothic mold. He also has a feel for white-trash anthems, like ''Friends in Low Places,'' in which a likable clod declares, ''Blame it all on my roots/I showed up in boots/ And ruined your black tie affair.'' Like Elvis, Brooks knows how to make lower class sexy. A

