Charles posted about maybe publishing his Westerns under a pseud, and collected some comments. I started replying, and as often happens, I ended up with a lot more verbage that is usually polite to post on someone else's blog, especially when I'm coming from the POV of headdesking at what some of the commenters were saying. I've also seen similar discussions elsewhere -- it's not just Charles's crowd -- so I'm posting here instead.
There seems to be a line of thought that says that you *should* publish everything under your own name, that if you write multiple genres, then the real readers, or your real fans, or anyone worth considering, will read whatever you write, or at least give it a try and then figure out for themselves which of your genres they like and only buy/read those. Or something. The thought seems to come from some principle of Writer Against the World, or Artiste Refusing to Sell Out, or some similar ego-war where giving in means losing. Or something.
In actuality, this is about marketing. Sorry, I know I just lost all the artistes, and most of the fierce individualists, but I'm talking to the writers who want their work read (and maybe even paid for) by lots and lots of people.
Anecdotal data, collected from a wide range of sources as opposed to just one writer and their close friends, as well as info from the big NY publishers (who do a LOT of things badly, but do have a buttload of marketing trends data) shows that a large fraction of the audience reads only one genre, or maybe two, and does not want to read another genre. I've run into people like this who will get angry about feeling OMGTricked! into reading a genre (or subgenre, or whatever) that they don't like because one of "their" writers (as if they own them) decided to write something different under the same name.
As a reader, I'll at least try just about anything by a writer I like a lot. So will a lot of other people I know. Strangely enough, most of these folks are writers -- people who are just that interested in fiction in general, and who are constantly aware of skill and style and craftsmanship, enough so to be able to appreciate a good story no matter what type it might be. There are many readers, however, who aren't like us.
Saying, "Well, I personally am different, therefore that's not true," or "I know hordes of people (which is actually like six or ten) who disagree with that, therefore it's not true," is an argument centered around ego, not data. Sorry, but it's true. Your or my personal feelings, or experiences with our friends, don't constitute a valid data sample.
Now, if there's something that strongly ties your work together -- frex., if all your fiction is pulp-style adventure, even if some is Western adventure and some is horror adventure and some is heroic fantasy adventure -- then you can build your name brand on that, because your target audience is fans of pulp-style adventure fiction.
If you're writing deeply scary horror, and rollicking adventure Westerns, and funny-ironic heroic fantasy, though, those are going to appeal to different audiences, for the most part. It'd suck of someone who loves funny-ironic fiction read one of your sleep-with-the-lights-on scary horror stories, and mentally crossed everything published under that name off their list.
This is marketing, folks. It's about getting your stories in front of the people who'd enjoy reading them, and be willing to hand you money for them. You're not in a battle of will with your readers, it's not an ego-fight, and publishing under multiple names doesn't mean that you lose, or you're selling out, or you're letting Those People dictate to you, or whatever. It means that you're taking action to make it easy for the folks who'd enjoy reading a particular group of your stories to find them. There you go, that's it.
And depending on what-all you write, it might also be about sequestering one or more of your genres from people who disapprove of those genres and would cross your name off their list because of that. Anything erotic is going to lose audience for your non-erotic adult fiction, and forget about children's or YA. Even within the same genre, people who write erotic romance and inspirational romance use different pseuds, because writing one will interfere with selling the other.
Saying, "Well, any reader worth having won't think like that," is... well, fine. If you're okay with chopping a chunk off of your target audience, then go for it. But realize that's what you're doing, and don't gripe about how your sales numbers never look like those of your friend with four pseuds, or like the more popular writers in your genres. (Unless you hit the big-time and become the next Stephen King or something, but counting on that is ridiculous as a business plan.)
If you write more than one genre, or more than one subgenre with distinctly different audiences, and there's no one strong style that ties it all together, give serious consideration to multiple pseuds. This isn't about ego -- it's about readers and sales. People who think there's some awesome heroism about being a starving artist sticking to his principles to the end can, well, do that. Me, I want to make it as easy as possible for people who'd like my stories to find them. Using multiple pseudonyms isn't any kind of failure, or selling out. It's a tool available to help you achieve your goals. Use it or don't, but be aware of what you're doing before you throw away a useful tool.