I'm in a small town in the UK, 40,000 or so ppl, with a fairly big (albiet underground) weed smoking community. I've never been worried about walking down the street with a fat one, if a copper goes by just cuff it (they never walk the streets, lazy buggers just drive around stopping folk for taillights out and shit)
I've never been busted, one time they came round to a friends flat (a bedsit with at least 10 of us in) on a tip off, about 15 mins after we'd smoked our last j and were starting to think about going out for some more. They had a good poke around, while we gave them all sorts of lip about not messing up the place (it was a bit of a dive) just cos we knew there was nothing they could do us for. They found papers, a roach book and a full ashtray but had to conceed that we'd done a good job of eliminating the evidence (not being too well off at the time, all joints were smoked right down to the roach) and left. Half hour later we were all sat merrily making another round of bifters.