I know they take a few vials of blood for testing as well as the bag of blood. If the tests show anything nasty they destroy (or send it for study if you've consented) the donated blood and would contact you so you could seek treatment.
They want as many people to donate blood as possible so I do think that since they are testing it all anyway, a lady who is paid for sex should have the opportunity to donate, but with HIV it can take up to 6 months before the tests will show anything and I'm not sure how long the blood is held for before being used.
Having said that, are there any non-biased studies showing how many girls are having as much sexual contact as us for free? And how many men they encounter in a year? I think it takes a lot of guts for an amateur to say "I've slept with 500 guys this year" don't think anyone irresponsible enough to have unprotected sex with that many guys would admit it the way a WG would. I can't blame them for wanted to use the info they have to protect people who are already vulnerable.
I mean following on from that, at least escorts (the responsible ones anyway) wear protection when they sleep with random men.
The sort of girls/women who go out to purposely get drunk and sleep around often don't wear protection, they are at risk just as much.
If that's the case they would either have to make the questions even more intrusive than they already are by asking about past partners and sex lives, which people would be put off by, or just accept they can't take blood from anyone.
It's easy to say that if she can do it, why can't I? But I think it's better to think that the organization is trying to minimize risks while still keeping the donor list as long as possible.
As good as condoms are they are not 100% effective against STIs, which is why most working girls go for check ups. I would feel bad enough if I caught something and could have passed it on to other clients and my partner without knowing it, but having someone out there who is already sick getting worse because my infected blood slipped past undetected.
If the Big Market Girls (local term for drunk girls who'll sleep with anything) want to give blood knowing the risk they cause that's between them and their god but personally I would rather think of another way I can give back and leave it alone. I would guess they know what they are talking about in terms of risk and while most WGs are sensible with protection just search B4 on AW and you will see it's not always the case.