I don't know how they do it in porno but after cumming more guys just aren't much into swallowing therefore I guess who goes first must be an issue. Some guys love to eat cum, some don't. A nice tip considering he may not be able to get hard if another call happens is always the proper gesture yet some on here think they're entitled to see a hot guy cum if they're hiring...
You can click on the arrow below and check another thread on the subject, this time about masseurs and what kind of HE is implied.
Gentlemen always tell if they're about to cum.