Some of the bias accusations were valid ten and more years ago when the Reform and the Alliance party were probably not treated fairly by the CBC. I think a lot of the accusations in recent years may be due to expectation bias and actually giving all the parties a fair shake. If there are 3 national parties (even though the greens are a rump party) and one regional party to the left of the conservatives, they are naturally going to take more than the lion's share of the coverage.
As a conservative, I think their national TV news coverage is pretty fair, at least at a host level. Peter Mansbridge and Evan Solomon are pretty decent moderators and present the facts well. I like the job that Kady O'Mally and Rosemary Barton do, even though I'm pretty sure their outlook is leftward of my own. Extending that, I really doubt that individually the hosts and reporters are anywhere near 1/3 conservative and thus representative of the Canadian population at a whole. Of that group, only Kevin O'Leary is the only one I know for sure is Conservative, but I really don't care as long as they present an interesting news show.
CBC radio is another animal altogether. There are some hosts that do not disguise their bias well, Michael Enright being one of them. For a sample, see:
http://www.cbc.ca/thesundayedition/essays/
If you listen to Cross-Country Checkup and went by callers alone you'd think that 80% of the country was Liberal or NDP (same could be said of their message boards), but I would guess from Rex Murphy's writings that he has become more conservative over the last decade.