It was like she was a parody of Lois Lane. They started by giving her all of Lois's bad qualities (because Lois can be rude and overbearing sometimes) but left out the good ones (her drive, her determination, her need to earn the right to be called the best). And they tossed in some extra annoying qualities besides. I sometimes got the feeling Lois was supposed to be SV's version of Cordelia Chase, the person who's rude, tactless and clueless, and says all of these insulting things to people that you find yourself laughing at almost in spite of yourself. The problem is that the SV folks couldn't write the kinds of awesome lines Cordelia had. And Charisma Carpenter hit those lines out of the park, which I can't really say for ED. (Although that could also be blamed on the writing.) So, because I didn't think Lois's "rude and tactless" routine was funny, I just thought she was obnoxious.
I didn't find the right solution from the Internet.