I can say, w\o hyperbole, that radical honesty ruined my life. Do not, I repeat do not believe that people are generally good, want to help you, will appreciate your honesty.
Now, I didn't do anything stupid like telling my boss that I'd like to sleep with his daughter, but, when he asked me where I saw myself in 5 years I did say that I wanted to start my own business.
Our relationship went from great to icy.
Over the next seven months my work life became a living hell. I went from "valued team contributor" to "does not function as part of the unit." My dedication was called into question and eventually I was told that the company had changed and that I was no longer useful.
I wasn't fired, but, I was left alone in my office, no new tasks were assigned, my medical condition was not accommodated, etc.
I eventually left my position, lost my gf because of it, ruined my credit after I couldn't find a new job, and have been unable to get loans to return to school (after leaving to help out my former employer.)
I often wonder what my life would be like if I had just said: "In five years I see myself working for you with only a slight raise!"
Don't try this at home.