Girls!! how often do you get skid-marks?

How often do you guys get poop on your panties? I know its gross... My Girlfriend threw her panties in my face the other night, and they stunk. ;(. I gave them a closer inspection, because I usually put them in my mouth but they had skid-marks. i was frightened by the thought that they were on my face, so I ran out of the room, and told her to take a shower. How many times does this happen to you girls on a regular basis, please let me know. Because if this girl is dirty or uncleanly, then I have to say bye bye.