In alot of cases yes. But its all about how they generalize, and bum is a bum, A Street kid is a street kid. but at the same time they have jobs to do (Mechanics anyway)But jus to cover the bases, think up Scenarios, and and practice talking your way out of them.
For example: Was caught in the yard one time, and had just finished peicing, I was on my way out. As soon as the bulls got out, I initiated conversation, went something like this...."Damn are you people ever gonna build a new Station ? That building has been there scince The Fortys!" "Whua" was there first statment. Next it went like this," I used to see my dad off from that parking lot every week, when he went out of town, That old fart is 50 years old, and hes still working here." Later on I explained I lived a few houses away, and a short cut through the yard, is always faster, beings how I know it pretty well.
Its all about letting them know you have some kind of corprete knowledge, and your not gonna be there long. I dunn know It worked for me.