I don’t have a credit card or score by the way.

They could be here legally (visa, whatever) and waiting for their green card.

I bet you did not have that one in your bingo card...

I accumulated about 50k in bills/expenses on cards during that time  and another 50k doing renovation on both rental property and my primary residence.

Obviously, dont put an unqualified person in there, but with record credit card debt in America, and a worsening recession on the horizon, one can expect much worse credit scores across the board vs 5 years ago.I have struggled to place tenants in my properties before, and have fixed the issue by adjusting my screening parameters. 

My current situation - I have a FICO of ~630 (no late payments or derogatory marks, just credit card debt from school). 

I have a Associate Degree in a completely unrelated field.Seeing as how we are planning to make real estate the foundation of our day-to-day income stream and long-term "retirement" strategy, it feels as if making another change of profession is in the cards.

If nothing else, offering a small reward like a gift card to their favorite restaurant (ask when they initially sign the lease) helps.

A Heloc is a open end mortgage like a credit card so its an additional trade line on credit, cannto never be used as an Asset, PITI reserve, and its a DTI killer in most cases.A heloc is also usually set up on a shorter term versus a mortgage, carries a Higher interest rate, and most carry a interest only with a prepayment penalty.

In Japan you can buy just about anything you would use a credit card or Yen to buy (actually that is true in many Asian countries, including Singapore where I lived for 10 years); Or back here in 'merica, we can even buy a Whopper at Burger King!