@Sue Duvall I suggest you go to a site for the residential assisted living academy in Phoenix.

They list properties on their own site, plus Airbnb, VRBO, Booking.com.

See what the $19k was for first, it may have been neccessary, but still that does not make it ok for them to do it without a signed CO.You can ask an attorney a few questions using sites like Avvo or Rocket for not much $$$.

Does this mean the realtor does not have exclusive rights to sell the property and the owner is probably advertising the same property on one of those by owner sites?

Again, the BiggerPockets store has some books on this topic, or you can learn about it by watching podcasts, reading blogs, and interacting on the forum.

I have a mix of MTRs, STRs, and a room rental and I can perform all the needed property management and bookkeeping features on the site. 

Either way it would be a grey area, selling a house with a different amount of units/bedroom/bathroom seems extreme though. its an auction site, I have seen auction sites miss the fact there was additional lots in a sale.

Here’s a BP blog for more info on this - 9 Vital Questions to Ask When Vetting Your Real Estate Investing TeamNo property ever paid the rent.

Basically, these are lands that technically qualify as Sending sites, but that have issues such that nobody really wants to build there.

100% worth it to post on Furnished Finder, but you need to make sure that you understand it is not a booking site.