Since no one responded I'll try to bump the topic and see if anyone else may answer this for me.

So this is a weird question but I've been wondering so I felt like I should ask it here... My girlfriend and I likes doing weird and exotic things in our life to spice up the relationship, and we asked each other to cum on a piece of clothing when we cannot meet so that we can trade some times and enjoy watching each other lick it or do other things to it. My question is, is that harmful to the human body? Me cumming on the same spot, and my girlfriend trying to lick old cum...

I'm guessing that this may be a perfect place for bacteria to grow. For example, urine is sterile when it comes out of the body, but it doesn't stay that way. Cum isn't sterile in the first place, so it can only get worse from there. I would think that ingesting it would be a bad idea. Also, if she puts it in her vagina, it may cause some kind of infection if it's old.