My girlfriend and I (lesbians) - use a strap-on (she uses it on me), and sometimes I end up more turned on after the first round than I was before, regardless of the initial teasing she puts me through.
That's when I just push her head between my legs, she usually gets the point
I think it's because of how she is. She gets SO turned on when using a strap-on on me, it's hard to get her orgasming out of my head, and it just turns me on again.