So, I think its definitely true that a lot of "bold" women are unfairly called bitches by men who resent their boldness.
However, there's also a group of women whom no one seems to acknowledge in the bold/bitch debate: the women who claim to be bold and claim suffering the bitch-label from sexist men, but who are in fact bitches.
I think the confusion stems from the fact that bitch and bold are actually composite characteristics. Bold is a combination of being assertive and compassionate, while bitch (or asshole, the male equivalent) is a combination of being assertive and arrogant. You'll notice assertiveness is a quality common to both descriptions.
One situation where this distinction really shows itself is in team projects in college. I'm sure everyone has experienced suffering under the leadership of an asshole -- a male who claims the leadership role, asserts a direction for the group, and completely ignores contrary opinions and input, even in the face of evidence that his direction isn't working. What's somewhat less common is a bitch who leads a group project.
I recall a group project in an Electrical Engineering lab where we had to build a line-following Lego robot. A woman in our group quickly asserted herself into a leadership role. However, her bitch-hood quickly became apparent when she repeatedly ignored my criticism of (and suggested solution to) a design flaw which was ruining the performance of our robot.
(Technical aside: the root of the problem was that we only had two wheels, and started with a design of a long and narrow "car", with powered wheels in the rear and skid plates (and sensors) up front.
the design was almost identical to the one in this video: http://www.youtube.com/watch?v=VriEXbuTbF0
Because the battery box / CPU was quite heavy, a significant portion of the weight rested on the skid plates. The resulting friction made the robot sluggish and prone to getting stuck. Further, the weight of the structure was causing the front end to frequently fall apart.
I suggested "Hey guys, I think what's happening is that we have too much weight transfer onto the friction pads. If we redesigned the robot to shift the weight more towards the axle, it would reduce the friction problem as well as the fragility problem". "No, we just need to reinforce the frame. That will solve the problem," said the bitch.
Now, I was auditing this class as a university employee, so I was older and more experienced than my teammates, and I recognized it would be doing them a disservice to simply take charge. The highest quality learning comes through experimentation and self-determined results, rather than simply being shown what the "best" answer was. So I backed off and let them try it their way.
Of course, the reinforcements only exacerbated the problem by shifting even more weight onto the skid plates. However, I felt it was important that they realize this on their own. After several hours with no progress, I chimed in again with the redesign suggestion, this time putting heavier emphasis on trying to explain the root phenomenon which was causing the problem, and trying to engage them in "what sort of design would result from attempting to reverse that phenomenon?". The bitch simply rejected this input again, and we all continued watching our robot get stuck and fall apart.
Finally we were nearing the competition deadline, and we hadn't made any forward progress. We had to make it through an entire maze, yet our robot couldn't reliably travel more than a few inches. I asked to be the overnight care-taker of the robot, claiming I wanted to "tweak the code a bit". I tore the robot apart and redesigned it to shift all of the weight over the axle, with two opposing skid pads on either side. This eliminated the friction problem, made the robot much more structurally sound, and actually ended up being one of the fastest and most nimble robots in the competition.
Here is a video of my redesign: http://www.youtube.com/watch?v=CT0YgOPJCDQ (please excuse the corrupted audio)
When I showed my teammates the next day, all of them were overjoyed by how much better the robot performed. Except for the bitch. She was silent for a while, and then became even bossier than usual towards the rest of the team, visibly angry. She said absolutely nothing to me.
I felt bad for taking over at the last minute (because that's a poor way to lead), but quite honestly, I knew I was right, I knew she was wrong, and I wasn't about to let this bitch's arrogance needlessly drive our grade into the ground.)
I think what happens in these situations is that Women, in a male dominated field, recognize the quality of assertiveness in the leaders of that field, and they try to emulate it themselves. However, some of them fail to recognize that simply being assertive isn't enough to be a great leader -- you have to be compassionate as well. You have to provide your team a firm guiding hand, yet still be willing to consider critical feedback fairly and objectively, and especially be willing to change course in the face of supporting evidence. No one wants to be lead by a bully.
Bold women are a very valuable asset, but bitches be crazy.