Am I liable as a homeowner if my roommate's dog bites another dog (or human) on the grounds of my condominium complex?

Will you get sued? Probably - anyone can sue anybody for anything. Will the suit be successful? That's impossible to say. I suggest that you require your roommate to have insurance on any pets that will cover bites or injuries caused by a pet and that they sign an agreement indemnifying you in the case of a bite or injury. Such an agreement should be part of any agreement you have your roommate sign. A local attorney can assist you in drafting the agreement. The State Bar of California can give you a referral: www.calbar.ca.gov/