I was with my wife, walking our two
When I talked about "naga hide", she had qualms about the main character. She said "women don't like snakes" so that might diminish the marketability/commercial viability. That certainly got my attention. Commercial viability = people paying money to publisher = happy publisher = publisher paying money to agent = happy agent = agent wanting to buy book = happy me. And the idea that women don't like snakes isn't untrue. I don't know what the statistics are, but over the world, I think it's more common than not.
So I started thinking of different monster girls that could serve the same role. Something that is both repulsive but alluring. Something traditionally seen as fundamentally evil, like biblical, with elements of seduction and demonry. Like a vampire or siren. Centaurs were too large -- I needed something that could climb and be disguised. Spiders had the same problem (also there's no compromise with women when it comes to spiders). Mermaids -- I already did a book on mermaids and besides, the medieval period wasn't wheelchair-accessible. Succubi are too on the nose. Dragon ladies are too powerful. Slime girls -- too sticky. Sheep-women were too silly, plant-girls are too out there, demon girls are too cliche. Not even bunny girls would work.
I finally decided on werewolf, even though 1) werewolves exist either in the camp of cheesy Universal horror movies or "Twilight" and 2) "Ginger Snaps" planted the flag on "female sexuality as the beast within".
I brainstormed bandages to my existing story ideas, but before I began full-on dedicating the death of brain cells to this, I asked Reddit's writing forum if what I was doing was right. If I should change a fundamental aspect of the character I originally envisioned for the sake of marketability. I didn't get a very large sample, but the sample I did get was vehement -- don't change your idea to satisfy someone else.
In fact, not one response supported the counter-argument. Some of the more memorable quotes: "execution > concept", "art is not a democracy", "write the story you want to read", and the one that really got to me: "From personal experience, changing an idea I have loved based on what I think would sell better has been nothing short of crushing to me." Nothing convinced me more than that. Can't deny user experience.
Quite a few mentioned the idea that "women don't like snakes" is bupkiss. Lots of responders said they love snakes just fine. No one said they were afraid of snakes, at least not from a book. And no one said they liked werewolves more.
And from these results, I'm glad. I feel like a dodged a bullet on this one -- prevented a lot more work than I would have needed. I'm glad I asked for advice, because I had a feeling in my gut they were right. And overall, I would have been unhappy all through the writing process. I wouldn't have been spending my time with the character I fell in love with.