I want guys to be just friends. How to make them believe that we can be good friends?

I wish to have very good friendship with guys. As many incidents have happened and i have lost my trust from girls. i talk with guys , but very formal talks. But when i try to have a good friendship they get a wrong indication that i am interested in them. I am talking to them doesn't mean that i have developed interest in them and wish to be more than friends. It don't happen with many gals but i don't know what goes wrong from my side. My politeness is misunderstood may be. I don't know. i am a bit soft spoken but i try to be friendly. I don't understand whether they are flirting or they are joking. If i a gal is open with hem they create a bad image of a gal that i feel is wrong. What they want to be just good friends.