Lawyers, bankers, and politicians wear suits. They're certainly trustworthy people.
If one means that a lawyer acting against one on behalf of another party cannot be trusted, well, of course. Such a lawyer is not acting for one. In that instance, one would instruct one's own lawyer, and that lawyer would be 100% trust-able.
http://www.guardian.co.uk/books/2013/jul/18/jk-rowling-anger...
Not exactly a common occurrance admittedly, but amusing you say that given the drama over this the past week.
We all "know" iffy examples. Doesn't make it general fact. Unless of course we have some stats that show lawyers are generally more self serving than any other walk of life. Do we?