Tenant referral; what can/cannot I say?

[Steven J.]

I'm curious as to what I can/cannot say in a tenant review with a new landlord. I know it can get you in a tough spot if you say the wrong bad things about an employee to a new employer - how does it pertain to tenants good and bad? 

Do I simply answer a new landlords questions with 'yes' and 'no' or do I go into details?