To test this theory of denture demand, I felt compelled to publish this posting on craigslist under the "FREE" section:
Free Horse Dentures (Northgate)
I've got a few sets of these horse dentures that I'm not using much and want to get rid of. Your horse will be happy to have a full set of nice, sharp new teeth. Or if you like, give them to the kids and they can have fun "horse mouth play time." Or, if you're strapped for cash and can't get gramps those dentures he's been needing, these could make a fine substitute.
I can deliver, e-mail me for more info.

* Location: Northgate
* it's NOT ok to contact this poster with services or other commercial interests
And sure enough, 2 hours later I checked my e-mail and had 9 responses! Here they are, completely unedited. And I SWEAR I am not making these up!
1. Nissa Cooley:
do you still have these?
im an aspiring taxidermist and these might come in handy...
thanks!
2. Vivi:
Hey, hello. I pony wrangle preschoolers rides on ponies, and story telling is great for kids. A few exciting props would be lovely. Vivi
3. Jim Kerkshaw:
I am interested in your dentures. Please call Jim at 206 334 XXXX. Thank you.
4. Luke Phelan:
if they are still avialble i would take them of your hands
call me 206533XXXX
5. Valerie Tavenner:
Hello
If you haven't given them away yet I would LOVE to have them for the
veterinary technician class that I teach in Renton.
I could come get them or if you'd like to deliver them directly to class
I am sure you would get lots of applause.
6. John E Lynch:
ill take em! when and where?
john
7. B. Gates:
Dear Sir:
I am interested in your free horse dentures, yet I do not believe they are truly for horses. Please advise.
Yours Truly,
B. Gates
8. Kimberlee Boring:
These would go great with my muppet creations (coming soon). Are the horse dentures still available?
Thanks,
Kim
9. Kim Pinnion:
i'll take them!
Unfortunately no one wanted to use them for "horse mouth play time," or give them to gramps as a sub for human dentures. Also, with the exception of "B. Gates" no one picked up on the fact that this was a cruel joke. I actually feel like kind of a dick now, as I realize there are people who really want horse dentures, and for practical purposes. If it's any consolation, I responded to each of these messages personally with "I'm really sorry, but they've already been picked up."
Well, I guess we answered the question in regards to the demand for horse dentures. Now tell me, am I an asshole or a cunning, clever genius?
UPDATE:
"B. Gates" responded to my apologetic e-mail with the following:
My name is Beatrice Gates and I have been a woman (in the biblical sense) for 14 years! I wanted those damn horse dentures. What are they for? I have to know, or I may die.
Thank you for your prompt response.
Love,
Beatrice