Hennessy's understand of what reclaiming a word means is somewhat incomplete. There isn't really a hope of changing the general usage or mindset, at least within many decades. However, as jollytiddlywink wrote earlier wrt "fag", the experience of being a person who has an offensive word thrown at them can change completely when one uses that word to describe oneself. The primary aim of reclaiming a word is not to change everyone else's usage, but to change one's response to that usage. For the people who choose to do it, it's one way of claiming back power and not accepting oppression. Reclaiming a word like "slut" would mean saying "so what?" or "yeah, so?" to oneself, at least, when called it. It's a way of stopping the policing and control which is really behind the motivation for calling someone a slut. If one doesn't care if one is called a slut, one has no reason to worry about behaving in a way which might cause someone to call one that. It's also impossible to dress and behave in a way that guarantees no-one will call one a slut, so it seems just a waste of time, thought and effort to try.
And yes, I would say that "slut" is a patriarchal concept, in that it's used to police and control women's sexual behaviour and/or appearance, coming from a mindset where women have a commodity value as a pure sexual item and are expected to give up that value to some suitable man who demands it in return for appropriate recompense (gifts, a family, etc.) I've heard "slut" used about women who've never had any sexual contact, seemingly because "too many" different guys apparently wanted sex with them. "Slut" is most often used by men to demean women, complain that their own entitlements to ownership and sex are not being upheld, and attempt to control so that those entitlements are met, and by women to emphasize that they are not like that, they are good women, in fear of losing the societal approval that is so damn fickle and hard to retain.
It's also important to massively question the use of the word "slut", because as I wrote previously, its usage doesn't tend to correlate with actual behaviour or appearance, but more with how much the speaker wants to judge and control. Quoting myself, mostly for diddums Hennessy who doesn't want to contend with the unknown that is unreg posts (and I assure you that G13 is the same writer throughout, as would be apparent from the style to anyone actually reading),
andPartly humorously, partly entirely seriously, a woman's frigid when she won't be sexual with the man who wants her to be with him, and a slut if she appears sexual with anyone else. And possibly a slut if she appears sexual with a man who another woman wants or whose friend wants.
Hennessy, what is a "slut"? Someone who has lots of sex, someone who's had several different partners, someone who's had different partners in a short space of time? All those definitions and more are used by different people. "Slut" is also sometimes used on a woman who enjoys sex, who's having sex with someone the speaker doesn't want her to have sex with, or someone the speaker just plain doesn't like. Consequently, I don't consider it a very useful word. I don't think it's ok to call anyone a slut, because it's shaming and policing. I don't think that women should be exempt: I think that people shouldn't be shamed for sexual choices that are consensual, not manipulative or deceitful. And I don't think "slut" is an effective way of censuring behaviour that's wrong for those reasons, as it's so sexually coded, it implies that the sex was what was wrong with the behaviour.
Hennessy, being a man, and one who has written nothing to indicate that he has any awareness or concern for women's issues and some things which demonstrate man-centricism if not misogyny, is on very contentious ground throwing the word "slut" around quite so much. It certainly doesn't come off as someone whole-heartedly supporting the reclamation, but as an immature male chauvinist delighting in the apparent opportunity at demeaning women, particularly those holding beliefs and advocating for rights in ways that he doesn't approve of, without fear of censure. This isn't that opportunity; Hennessy, you're coming off as a bigot, a male chauvinist and a misogynist. As such, "slut" from you will always sound offensive.
The issue that "slut" has a different effect on different demographics of women has certainly not escaped at least the vaguely thoughtful feminist spaces. There are a number of good pieces around discussing how and why "slut" can be very different to non-white women than white women, for example, and why non-white women generally wouldn't feel so "empowered" by reclaiming the word. Feminism in general is not clueless about this, nor about the fact that it is a movement which centres white, western, educated, able-bodied women. It's not as clued up as I would personally like, nor as active about changing it, but it is aware of the fact.
Believing that Slutwalk is first and foremost about reclaiming the word "slut" is a misconception. My first post on the first page gives a pretty good overview, and I'm not inclined to repeat it and annoy everyone else just because one (or a few) person doesn't want to read it. It's there.
My personal opinion is that "Slutwalk" is a problematic name outside of the immediate Toronto situation. However, I'm totally in line with the general aim of saying that victim-blaming is just not on and that women should be free to do what's right for them without fear or influence of the "frigid" or "slut" labels. At the same time, I'm fine with anyone who prefers to stay away because they can't associate with the name, and I do wish that that didn't exclude people; but this movement took off so fast and was truly grass-roots so that it didn't go through all sorts of committees and discussions to check that it was getting everything "right".