The rent roll was so close to 1% of list price (which in my opinion is too high to start with) that I was instantly interested. 

That would instantly change my mindset from skepticism into excitement.

I'm sure I'm missing some other options, but none come instantly to mind.

The annual returns for example are an instant red flag.

Instantly I can tell the hottest markets from the normal and cold ones, and separately determine which one's I am priced out of due to crazy high values.I'd suggest a similar value-based approach if you have the data to calculate on to identify a few markets to start looking for deals in, but remember this is still too broad of analysis to make a go/no-go decision on the projects you find.

On a similar note, it seems like so many STR hosts, posting on this forum, do Instant Book and are otherwise very lenient with who they allow to rent their property and "never have any issues". 

I'm getting my finances in order now so I can buy the house that I've been renting from my in laws and will have instant equity.

Instant water heaters take up less space and come in electric or gas versions.

A strict cancellation policy and never allowing Instant Book have worked best for us.  

You have to know when your initial text goes out, because the response is going to be instant, and you better reply to their reply instantly, but if you don't know they are going out then you cannot make sure you are there.