My brother lived with me up until a few years ago and we kept our bikes in our shed (which had seen better days, the trim and bottom were starting to rot through). I never thought that in our nice quiet neighborhood I would have to lock them inside if the shed was already locked. Well the teenage boy next door had some friends who were not quite upstanding citizens and the one busted our shed doors in, trashed everything, and stole his bike!
It was as inexpensive of a bike as you could get (a Walmart brand Nexxt 'mtb' with suspension that was the best we could afford at the time he was learning to ride,) but it had a pretty blue and silver paintjob and with the shocks I bet it looked pretty nice to a young kid who didn't know anything about bikes. They left my old Sears bike (that was plain red and pretty beat up, plus it was a girl's bike). So we call the police, ask around the neighborhood, etc. but don't find anything out. Then a couple of weeks go by...
And the moron shows up nextdoor on the stolen bike, he just painted it flat black!!! Rims, reflectors and all, everything! I just happened to be taking the dog out and see him on it, I confronted him and got it back (idiot still tried to claim it was his and attempted to ride away on it!) My brother didn't want to press charges, I did speak with the boy's mother who insisted that he never did anything like that before and the other kids had told him about the bike first. (Well if people tell him there is money in a bank does that make him not responsible if he goes out and robs the bank?!)
Sorry for the rambling, I just hate thieves and had a car stolen twice (yes, the same car! when we lived the next city over) but my point is that no matter how nice or crap your bike, someone will take it if they have the opportunity. Shed doors are rebuilt and everything is locked to wall joist anchors with OnGuard D locks and chains (even the crap Sears bike and spray painted special are super locked up, if they are stealing a bike it won't be mine even if it is scrap now!!) Also any time I see a bike with a crap repaint job I think it is probably stolen, not that it is scruffed up as a thief-deterrent.