Don't do it!!
I've done this many times with a couple that I swing with where I am the third party doing her doggy. My dick and balls are all over the husband's face. My balls usually rest on his forehead.
I am not gay or bi....not even close... so, I do not enjoy such contact. I question whether the hubby enjoys it...I'm not sure about him!
For the wife...she is in ectasy. her hubby is an oral expert and I've got a huge dick. She loves this position. This is the highlight of her week...we usually finish the sex session with her licking my asshole while I stroke. I always cum in her mouth...