Two part answer. Black panties and creamy streaks/stains. First on an given day any number of things can cause a woman to leave residue which is oh so much more visible in black
For me a narrow 1/4 inch or so and as much as 3 inches long just means the panty got up in between my lips when I was hot, I got aroused, or was close to my monthly cycle.
Now a wide seam to seam oval mark was most always caused by the leftovers dribbling out afterwards
So don’t automatically assume the latter that is unless she cleaned up before putting them back on.
