I agree with @Jonathan R McLaughlin, I'm not too concerned with the actual score, I'm looking into the details. How many open accounts, what are current monthly commitments? To me that is more important that their gross income being 3x of the rent or their score being a certain #. Let's say rent is $1,500 and they make 5k. If they also have $800 in car payments, $500 in credit card payments, $200 in medical debt, $350 in student loans, etc. You get the point... on paper their gross income would exceed 3x the rent, but they are up to their neck with debt and will probably have a hard time scraping by.
Also, what were the defaulted accounts? Were they medical bills, credit cards, etc.? I don't think it's uncommon for renters to have poor credit, if they had good credit & good income, they would probably be in the market to purchase. Whenever we see things that concern us, we ask for an explanation. Maybe someone made a mistake a co-signed on a car for their kid and wasn't able to cover the payment when their kid defaulted.
Prior evictions are a big red flag, that's probably someone you want to avoid.
Also, I want to see reliable work history. If I see someone at the same job for 5+ years, that's pretty good. However, if someone has had 3-5 jobs over the last 5 years, that can be a little scary. Why are they moving around so much? Is it by choice because they getting better jobs, or are they getting fired?