well, to get odors off of skin, you can rub a quartered lemon over the offending skin or two teaspoons of lemon juice rubbed over the skin for 30 seconds or so, then rinse. it's possible your girl was getting a yeast infection or was close to her period, as both of those things will change her normal scent. or something else may be wrong and she may need to see her doctor. i'd think it's something she'd notice and take care of if it's abormal. the other possibility i guess is that you two could take a shower or bath together before any kind of sexual activity to see if maybe it was hygiene related.