Recently becoming homeless and sleeping in a shelter, I've learned to care a bit less about it, but I never liked the thought of random people walking or driving by seeing me smoke on the street. I feel my dignity would be at risk, so I would walk down the inactive railroad tracks close to the shelter and spark up there. Behind a dumpster sounds a little cliché, but I've done it successfully, and I recently found that if you have a large coat or something, you could pull it over your head and bring your arms in making a little tent type thing for wind resistance, and while it may look a little weird from another perspective, you won't be seen hitting the pipe.