What does discharge from pid usually smell like? i know it's bad smelling but what could it be compared to?

Fishy, usually: Pelvic inflammatory disease itself doen't cause a particular kind of discharge, but many women with PID also have bacterial vaginosis, an overgrowth of vaginal bacteria. In some cases, BV may trigger PID, along with gonorrhea or chlamydia. BV typically causes a fishy odor. In fact, the vaginal bacteria produce some of the same chemicals that create the odor of decaying fish.