Bambina I can see where you are coming from on this too.
I get frustrated also. But then I moved on. Just say they aren't for me.
I think why people just ask you BDSM related questions then personal is because there are certain subs or doms they are looking for, depends who they are. Once they find something they think they "clicked" with then probably things would get a bit easier to get to the personal part. That's my opinion.
Hope you find someone suitable for you.