been there be careful =the police work with the dealers who try to get you to buy while the authorities are sitting down the street watching/they thrive on busting tourist and getting the bail paid in cash.
I am sure if you are careful you can find someone bit the dealers are making more on the kickbacks from the popo.
You WILL be approached if you are tourist looking ,just scan the surrounding area and chances are you are being watched. Also some of the undercover cars the police drive in are taxis