Generally speaking there is no magic FICO score that guarantees a clearance. Average credit ranges from 630 to 680. If you are below 630, you have dings. If you are below 500...you have damage. I normally feel comfortable sending forth a package if a person is a 650 or higher. 650 is "fair,"' and some classify 680 as "good".
Addressed and unaddressed debt is the bigger picture. Any of us, cleared or not, can have an unknown debt go to collection (myself included). The ticket is resolving said debt upon discovery. Moving it from unaddressed to addressed. The SF86 is set up to walk you down a path of yes I have this late or unpaid debt, and here is my repayment plan. Not plan to get into a repayment plan, but here is the monthly payment moving forward. I recommend applicants check their scores to make sure there are no surprises, look at creditor listing and challenge anything not related to you, pay off any low hanging fruit bills of $15 or $25, and then get into a re-payment plan on bigger ticket items. Consistently making payments on time and not exceeding normal debt to income ratios will quickly make scores rise with the newer formulas.