May 21, - How sex affects vaginal odor. Some women notice a strong fishy odor immediately after sexual intercourse, which is a telltale sign of bacterial vaginosis. Others notice a less distinct smell. Sometimes interactions between semen and vaginal fluids can cause vaginal odor. Sweat, female 'lubricant', male ejaculate (does that even smell?) and latex. I dunno how, but if I walk into a room and someone has had sex in the last 4 hours.