It's true, but sometimes that is also when the most truth can come out. Most people tend to say things aimed to wound, but sometimes when pushed is indeed when the most truth comes out of them. It depends entirely on the person and the situation.
It happens all the more frequently when I'm furious that I state stuff I don't mean. It relies altogether upon the individual and the situation, but now and then that is likewise when the most truth can turn out. I attempt to keep my temper, however some of the time I lose it.
That's why I don't talk too much, because if you push me that far, I will spout out words I don't mean. I'll apologize later if I think what I did was wrong, but if you piss me off, I will mean what I said.
I want to say it's one to one, but in all honesty I'm a bit fuzzy there. I can recommend JoyFreak's sister site AdminIntel - Admin & Webmaster Resource where there are lots for people of varying degrees of expertise with development, you likely can get a far more precise answer there!