I have always thought it was kind of pointless to call their current landlord since they are going to give me a stellar review of their rental history if they want to get rid of them.

The rest is history. 

So I get this referral from a relative about a tenant who has good credit score, no criminal history, and a good paying job.

I recommend reading into the history of Helocs during the GFC.

Solid employment history.  

Verifying last 2 years of rental history very important!

Show them the history of 30 year fixed mortgage rate & explain that the only reason rates got as low as they did is because the Federal Reserve started Quantitative Easing during the during the recession and then again during COVID.Here's the graph showing the impact of Quantitative Easing (QE) on interest rates.

HELOCs are much tricker than a closed end second - they don't typically allow you to close in an LLC and they are full doc qualification, meaning your FICO, employment history, income, DTI etc all come into play.

Also, many tenants are younger and have limited credit history.

Verifying last 2 years of rental history very important!