Well, there's always the option of supporting other works even if you stick with a show or a fandom that largely reveres its own brokenness in this context. For example, (http://dark-agenda.dreamwidth.org/profile)dark_agenda (http://dark-agenda.dreamwidth.org/) is a good resource for thoughts on responsible writing of CoC, among other things, and it keeps a database of fandoms open to submissions. I've been really impressed with how cogently the community maintainers and members put together the Diversity in Yuletide 2009 Challenge (http://dark-agenda.dreamwidth.org/1376.html), which is one of several posts in the community with solid resources on offer. Since that community is about promoting chromatic sources and creators in fandom, this is one of the maintainer's bullet-point lists from that post -

Our suggested hierarchy:
First, write for a language and culture other than your own.
Second, support sources that are as authentic and unproblematic as they can be, especially in relation to those made about a culture from outside it.
Third, celebrate actual source cultures before reinterpretations of it, because there just isn't enough of the first; i.e. realistic representations before retellings of myths, and actual religions before fantasy send-ups of them.
Fourth, if you end up writing problematic source, engage in fixing it: finding the invisible people of colour and putting them back in, writing the back story for a character without tying it into the white people's narratives, showing not telling the blind spots and bigotry and flaws in the celebrated white heroes of the narrative.

It does, of course, take more looking around, and more effort especially if you choose to write - and the fandoms tend to be significantly smaller, as I discovered for shows like Little Mosque on the Prairie, or movies like Imagine Me & You or My Beautiful Laundrette. But I do think it matters, even if the creators of SPN or Stargate hardly notice and care even less about what we think. What we think and create matters in the sense that it always matters how we express ourselves toward other people, and it's only if we keep working at it that we keep pushing the boundaries in our own heads, and in anyone else's. So, uh, support your future (or current?) screenwriter trying to tell stories about people other than straight white dudes? The whole endeavor may seem Sisyphean, but I have to feel a little hopeful when I watch pre-Code films and female characters remain alive and unpunished for stuff like murder at the end of the movie, etc. Well, it's either feel hopeful or feel depressed that things have gone backward in some respects for representational politics in film since... eighty-some years ago. But, you know, as above, keep the flame alive!

I was thinking of Jo and Tamara too, but yes, it's pretty clear there are no Winchester equivalents. Re: lynching - you are right about the drain cleaner. So, a black man is killed by being forced to drink Drano, while surrounded by white people. I... my reaction to that was the same as Betty's: Jesus on ROLLER SKATES. This could not present more like a lynching without a piece of rope present.

One of the reasons why high up on my list of Episodes I Really, Really Want But Will Never Ever Get is the Winchester's encounter with an alternate universe with a genderswapped Dean.