It's like anywhere else, you just gotta feel people out. Don't "try before you buy", then you are roped in. Look closely, smell, and most importantly haggle. It can be had for great prices if you're willing to walk away. Don't tell anyone where you're staying, don't give too much personal info, even if it seems innocuous. You won't be set up, but getting ripped off is a possibility. Never give money up front, always see what you're buying.