Absolutely right. With most of those tests, especially the older ones like the MBTI, there's a no better than chance possibility that it'll predict behaviour or reactions (ie. it won't).
The online ones are all so different, and usually poorly made, that it's perfectly possible to get entirely opposite results from two tests each claiming to be the same. I've been male, female, T, P, and every damn' thing under the Sun according to them. The psychological-gender one the BBC did lately was good, and I'm not just saying that 'cos the bloke who wrote it is the one who marks my work *cough*
What I was, slightly cryptically, trying to point out was that people's attitudes, actions and reactions are down to their personalities far more than their sex. I think we (mostly) know that full well. Unless we're from Venezuela, possibly