"God gave man a brain and a penis, but only enough blood to run one at a time." This is never more true than the number off mongers that will throw caution to the wind with respect to their future health when it comes to engaging in BBFS with Kgirls. When men have a boner, they don't think straight, and the posts on BBFS boards proves this. I have personally known 7 LA/OC Kgirl mongers that caught HSV2 from Kgirls. These BBFS fans will be quick to argue that guys catching something from a Kgirl is a very small percentage. It may be a small percentage of the cases that are REPORTED, but we don't have any idea of how many guys have caught STD's who didn't tell anyone, or more concerning are guys who catch something and just keep doing BBFS. I have talked to a few that admitted they had contracted HSV2 engaging in bare P4P, so their attitude is "I'm already infected, so I don't have anything more to worry about." Obviously, they could care less about infecting, you, me, or any of the Kgirls, as long as they continue to get BBFS from some of the girls.
We each have our own threshold for risk, and so its up to each of us to decide for OURSELVES how much risk we want to take. My threshold is easily defined. I don't go bare with girls that advertise BBFS or have multiple confirmations of BBFS on their menu on various boards. In other words, while most BBFS-hounds chase the girls that are KNOWN to offer BBFS, for me, its a "Do Not See" list. I mostly will only go bare with a Kgirl that I have an outside BF/GF relationship with or with a SB I am seeing. (Most SB's see guys serially, not contemporaneously). There have been a few others over the years that have invited me to go bare after I have known them for six months or longer. Other than these three situations, you have to assume that any girl going bare with you is also going bare with others, so how much risk can you tolerate? These girls see six to eight mongers a day, times 6 days a week, which can add up to over 150 different guys per month. If the infection rate is only 2 percent, as BBFS fans claim, that's 3 guys a month for EACH Kgirl that are likely to catch something, so again, how much risk can YOU tolerate?
I think your main question is how prevalent is it? Up until about three years ago, NO Kgirl I ever met wanted it known that they engage in BBFS with ANYBODY. Then an aggressive booker in the Bay Area started convincing new girls coming here for the first time that they will get a lot more business if they put BBFS on their menu for everyone. Accordingly, the ad profiles would use the term PSE to identify these girls, while the traditional GFE moniker was used to identify girls who do NOT offer BBFS. This practice has just started at a few of the agencies here in Los Angeles about a year ago.
A few short years ago, bookers would Blacklist you for asking them OR the girl for BBFS. Some still do, but others have gotten more lenient and may even give you an answer as to whether the girl offers it or not. Just be careful about inquiring because you are still more likely to get BL'd than to get info about BBFS.
The thing that has destroyed a lot of the opportunities for BBFS is the habit among mongers (and this is facilitated by some of these BBFS boards at other sites) to "out" girls that don't want to be outed. A girls agrees to BBFS with a guy and asks him not to tell anyone, and the guy runs right out and posts that the girl offers BBFS. This has had the chilling effect of encouraging girls that USED to offer BBFS on a YMMV basis to take it off the menu for everyone, even guys they used to do it with. There are dozens of posts confirming that girls are REMOVING this service from their menu because some guy "outed" them on a public board.
One of the things that I find amusing is that there are a few guys over there that think they are completely safe (and some swear by using DATY to get a girl "in the mood" for BBFS) by being the her first appointment of the day. I have had several Kgirlfriends that lived in Ktown and worked in Ktown/WLA areas. They come home at night just like with a regular job and go back to the incall in the morning. I have always spent a few nights a week at their apartment, since I am their real-life boyfriend. In the morning, I would have sex with her BB-CIP and I would go to work and she would go to her work at the incall. I always smile thinking of one of these "gurus" telling guys always be her first appointment of the day going down on her and cleaning out my load. There's one guy in particular over there shilling for booker M that has probably swallowed more of my cum than any Kgirl has. Since he loves to "out" Kgirls on BBFS, I call that poetic justice. Lol