I don't entirely agree with your irony (unless - and I've only seen this on TV... in fact I think only in the simpsons - do blood doners get paid in the US?)

Certainly in the UK, where there is no benefit for giving blood, I can only assume that those who lie about it are doing so because they too know (or 100% believe, possibly incorrectly) that they are clean, and they don't want what they see as pointless policy to prevent them from helping others.

Here's the problem with just saying "are you clean?" You could be in a long-term committed monogamous man-man relationship, and therefore believe you are completely safe. However, the fact that you trust your partner not to cheat on you does not mean that health authorities can trust him not to have cheated on you. So even if the person being asked is completely telling the truth, they might be wrong.

You can't think of any reason somebody might lie about being gay if they aren't paid money to do so?

If I were in the closet then, on discovering the MSM issue with donating blood, I would (assuming I had peaked far another out of the closet to have a MSM encounter) not donate blood, I wouldn't think "well I was going to, and I don't want people to think I'm gay so I'd better go through with it".

I think you're missing out on the term 'in the closet.'

You can get paid for donating plasma.

>men who lie at the blood bank. //

Isn't the only real reason to lie because you're doing it for yourself and not really to try and help other people?