tangier in morocco. you get of the ferry and 90% of the people you meet on the first day try to rip you off in any possible way if not steal your stuff, money, phone anything. by far the worst place i've ever been too.
one taxi driver tried to drive away with our luggage in his trunk, a girl we've met on the ferry that stayed with us for some time got betrayed while changing money, 5 minutes later she got betrayed again while paying for a cab. people going for your pockets all the time, people asking you to come with them to see their appartement/restaurant/cousin whatever all the time, people trying to steal your camara gear, fake cops, real cops making you pay weird tickets, busdrivers charging you triple prices, weird dudes trying to sell you any kind of drugs (but have deals with the cops and you'll end up in jail or in front of an ATM to "bail out" 10 minutes later).
the rest of the country is really chilled, but that city is hell.
also a certain parts of barcelona at late at night.
spending the night sleeping at a beach in portugal i woke up while some gipsys tried to steal our stuff, they left with my friends vans halfcabs and an independent hat.
the place wasn't nearly as sketchy as waking up while someone searches your pockets.
i remember paris suburbs beeing sketchy as well.