dittany, I was one of the "innocent until proven guilty" posters you refer to, so I'll just explain what I meant by that, and apologise if you thought I was word-twisting - not my intention. What I meant is:
A man accused of rape, wife beating etc who is pleading not guilty, is assumed by our legal system to be not guilty until he is convicted.
Unless he has confessed to the crime to you, as the defence lawyer,, or unless he has a previous conviction for such offenses, I would say you cannot call him a rapist, wife beater etc until said conviction has happened - he's a man accused of rape, wife beating etc
Thus, as a lawyer, you would have no way of knowing if such men are in fact rapists, wife beaters etc until the trial is concluded. So how can you tell if you are depending a rapist, or an innocent man (and, BTW IMO, you are more likely to be defending the former rather than the latter in court)?
Of course, once you've taken the case, I presume you can't ditch once your client is found guilty. Personally, that would be why I as a woman would have a problem with working as a defence barrister, but I also shudder at the thought that courts become boys clubs, which I suspect they would if the only route for women was as a prosecutor. I also shudder at the thought that I would be grilled by a male defence barrister. So no easy answer for me, just a case of, I couldn't do it myself.