Many other have warned about HOA's...stay away from any neighborhood that doesn't have an HOA and isn't zoned specifically to be STR.

On the other hand if they are a sponsor that is experienced in stopping a skin in the game, that's a huge red flag for me.c) how open to scrutiny are they?

Avoid purchasing in Rent Pressure Zones if possible in order to make things easier with the permitting. 

Make sure to check zoning laws and permit requirements in your area, and maybe connect with local contractors through referrals to get multiple quotes.

Get out of your comfort zone.

One of my biggest red flags when dealing with lenders is lack of transparency around fees.

If the prospect puts up a big wall and is dismissive about their record, that is more of a red flag than the record itself, but if they were straight forward and honest with me, I will know I can trust them.

Then red leg partridge hunting for 3’days.  

Cycling the red rock loop.

They are located in a hurricane zone.