I have given head to quite a few guys
I am a guy and one of the most common things I hear from them during and afterwards is they have never had anyone suck on them and make it feel so great. The second thing is almost all of the men I have sucked to a second orgasm have never had that done to them. The women swallow the first load and are done.
The second orgasm to me is always their most powerful one, I have heard them moaning like a woman when they finally have it as I suck away on them. One guy asked me after probably forty five minutes of straight sucking if he could come back tomorrow because I was magnificent.
I have managed to suck a few guys to three orgasms but that is about my limit because that is a lot of sucking.