Agreed AsnDragon, just for two recent examples that go to this point, I posted a reply to a few weeks ago to a punter who was praising a 141 walk-up girl in Sheung Wang and mentioned good DATY w/ her. I saw the same girl the previous week and had pulled out almost immediately after starting in mish as I noted greenish streaks on the condom after the first few thrusts. I always make a point to pull out completely after the first few just to make sure there's no discoloration on the condom (as noted above it's generally going to be whitish or greenish when a girl has an LB infection or possibly blood). Personally, I've never even thought about giving a 141 walk-up (or walk-in) DATY as they've generally been in use a long time and operate outside required medical inspections / oversight. Anyway, that’s just me and to each his own.
Another recent incident involved a WG at D1. A similar situation where I went down to kiss on the sides of her nearly hairless bush and used thumb to move around her LS. However, observing her LS after from the side during this foreplay allowed me to notice some fairly dense white discharge coming from her vagina. It clearly wasn't the good kind (which would be lighter, more translucent and have a familiar pleasant smell). It didn't smell bad so, when I brought it to her attention right away, she said it was medicine and gave a rather evasive answer as to why (same as the 141 walk-up girl above said about the green stuff). That's absolutely fine with me as I recognize it probably embarrassed the girl or, at least, brings up negative emotions for her. I sympathize that they don't want to stop working when infected w/ something though, on the other hand, I do not sympathize at all with the fact this puts their customers at risk (and, of course, themselves, by continuing to have sex when they're not fully healthy).
These experiences go to show that DATY and certainly BBFS do carry risks that should be well understood beforehand. It isn't like every WG takes a break to get 100% healthy when she has a problem. Most probably don't stop any longer than necessary as they're trying to maximize their earnings. So, medical days off carry a high cost and one that many girls aren't willing to absorb so long as the problem appears manageable. Also, many WGs might not be well informed, get proper medical advice or get regular checks. In many cases (eg, chlamydia, HPV/genital warts, syphilis, HSV-1 & 2), the symptoms vary substantially in different hosts and it isn't uncommon for symptoms to go unnoticed or be mistaken for something else (or just go into remission before being treated). I assume many of those with experience who "checked out the kitchen before dining" (whether b/c one intended DATY or was just taking a look in the course of warming up before a session) have noticed LS areas w/ a red blemish here or there (which I find WGs often dismiss as pimples...maybe), a couple of small discolored bumps (possibly HPV) or the type of discolored discharge mentioned already.
Keep in mind too that STDs, like all viruses and bacterias, are evolving and in many cases becoming stronger and more difficult to treat.So, the cost of contracting one could be higher than expected. A good friend who's a doctor in Taipei has related the increasing difficulty of treating regular bacterial infections that patients contracted through DATY and sex (including protected sex whereby the bacteria was transmitted to the surface of the pubic area rather than internally via the tip of the penis or due to a broken condom). There is much medical evidence of this trend to the point it even showed up on the bottom of the front page cover of the South China Morning Post 2 weeks ago in an article tracing the evolution of a highly drug-resistant strain of gonorrhea that doctors from Japan to the UK were struggling to treat. I assume we all know that gonorrhea (along w/ other STDs) is not 100% confined to genital transmission (ie, DATY does carry real risks).
I don’t want to preach and I’ve certainly taken more than my share of unneeded risks but, for more info, here’s a helpful link on this topic:
http://www.cdc.gov/std/general/default.htm