You could take some existing houses and buy and sell to each other within the group of investors to create comps and churn.
The transaction costs could mount… but you can list on the MLS for a couple hundred dollars… Do that a couple of times to make it look like a flipper flopped thus driving down values.
I think the key is to keep it quiet and not tell anyone about it. Realtors have big mouths so don’t count on them to keep a secret.
Now that I think about it, one could sell to a relative in an “arms-length” transaction to permanently reset the property tax basis to a lower level. That’s perhaps a good thing to do at the bottom.
For example, on a house that is paid off, you can create a mortgage and have the lender foreclose or do a deed in lieu of foreclosure. Parents can foreclose on a house owned by their children if they are the lender.
Deeds are not required to be recorded (they generally are to protect priority and ownership).
Anyway, one can get pretty creative. Nothing wrong with that as long as it’s legal.
God knows the Realtors have tried everything in the book.