The answer is "when all players are losing money"There isn't just one STR market in a given area.

Affordability will continue to be an issue for your larger markets and much less competition from the big players in smaller markets. 

A bank of course is interest only on drawn funds.As HML have gotten very competitive the bigger players have the money to buy the proper software to allow them to do the math on drawn funds and interest on days out..

A lot of flippers will lose money or hire ****** contractor to do work.In major cities, big players still developing and building.

I am thinking that the BIGGEST players are those you never hear about.They are quietly making a fortune in their corner taking over the world!

All markets are simply supply & demand + price discovery; a major player just moved to only one side of the market.

There are a lot of established players in the space that have reputations with wholesalers and cash to buy.  

There are some very strong players in this post.  

You just have to go to the auction and see who the players are. 

To @John Underwood's point, Airdna isn't entirely accurate but they usually come in on the low end so you can always use this as a baseline.Also go with any one of the vacation rental insurance providers he mentioned.Airbnb charges you 3% if you're a small-time host, or 15% if you're a bigger player.