I've only made a few trades. They were proposed by more experienced players, and I don't think I was taken advantage of, but with my level of expertise I can honestly say I'm not sure.
I've offered a few trades that I thought made sense that haven't been accepted. I didn't think they were ridiculous. My hope would be that if I offered a dumd trade, the other player might let me know exactly why it was dumb.
That being said, I can't envision a scenario where I'm offering up Bonds for Cristobal Torriente and and Jim Thome. Or Vice Versa.