My $.02 (about what it's worth) as not only a "landlord" but also as a recent divorce' whose credit got lambasted during the process of the divorce.
1. What are the types of accounts in collection? Is it medical? I cut some slack on those. It is vehicle? Is it utilities connected to the cost of living? Is it something that can cause wage garnishment? Life happens in regard to medical emergencies. However, if basic cost of living expenses are not met and have gone to collection that is not a good sign. In those cases, I make a tenant pay those outstanding collections and bring me proof of payment. This not only shows me they will "make good" on their debt when pushed, but it will also show me they REALLY want to live in my place and will appreciate it. It also has the psychological component of letting them know that if they skip out on me I will not hesitate to come after them myself.
2. The issue of the house - as explained to me by my divorce attorney: The judge may have ruled the ex is responsible for the house. However, banks do not usually recognize that and will take both loan holders accountable and then force the "innocent" ex to take the ex back to court for reimbursement for costs associated in the violation of the court order.. Make sense? She needs to have the courts order he refinance the house and take her name off the mortgage.
3. As to the credit score: This time last year my credit score was 817. However, due to the divorce process, no financial support from the ex or help with the medical needs of my special needs son, I had to max out my credit cards. So even though I never missed a payment or was even late on a payment, my debt to credit ratio was completely upside down and that hurt me. Granted, my credit card debt is now gone, but it will take me some time to get my score even back into low 700s.
Hope this helps.