As others have said, it seems to be something that occasionally gets a mention in US porn, when an occasional foreskin is sighted by the participants. However, in non-US/European porn I don't think that I have ever heard anyone (male or female) comment when they come across a circumcised cock. Strange because when I first see a mate's cock for the first time, especially if they are circumcised, we often have a brief conversation about the timing/reasons for etc etc. - just out of simple curiosity.