When younger I took things at face value but question a lot more now. I do think I'm more laid back though..... life's too short to worry about things you'll never change.
Depends on the situation. We are open hearted to genuine folk and hard as nails with people trying to con us (like the guy who tried to sell a new drive today at 50% off (what????).
As you get older its natural that you learn to spot the bad guys but cynicism as a way of life- never!
My first reaction is always to accept people at face-value (politicians excepted), but I have learned to be cautious as to how far I trust them and admit them into my confidence. It is, sadly, experience and realising that I was open, others weren't.
I don't think I have got more cynical. When you have learned more, you tend to know how things will turn out when its not going to be good. But that's knowledge, not cynicism.