The compendium mentions hiding is depending on skill level, and also "the amount of cover available". I've noticed I can occasionally pop a hide with 0 skill, what else affects it and what qualifies as "cover"?
If you're up against a house wall you get a good boost to success, not sure how much though. Also bear in mind that even with 0 skill points assigned you will have about 10 - 25 ish hiding skill due to your stats.