What could be some determining factors for your SSBI to fail? What do they generally look for when making the determination?

The primary reason they look at your credit report is to determine if a foreign entity could use your financial situation to either bribe or blackmail you. It can also reveal any problem(s) you might have with impulsive or reckless spending. They're concerned with parking or moving violations, because that could indicate recklessness, as well as how responsible you are in regards to paying them off. Depending on how long it's been since your last SSBI, they may only do cursory personal interviews with the contacts you listed; they usually only ask brief questions, then ask your contacts for names of OTHER people who know/knew you. They know the folks you listed will give a good report, so they want more from people who may or may not have your best interest in mind. Overall, investigators are looking for evidence that you lack self control or are easily controlled, are deceitful or easily deceived. As has been discussed before, THE NUMBER ONE reason for disapproval is lying!! Trust that anything 'negative' in your submission will be found out; it's IMPERATIVE that you come clean from the start!