People in bad neighbourhoods are more likely to either leave you alone, steal from you, or beat you up. Your chances of being killed are very small. Most killings are usually targeted towards specific individuals, such as members of rival gangs, not random people. If you were to start throwing up random gang signs they'd probably think you were just crazy and walk away.
It's also important to note that most people from bad neighbourhoods includes a lot of famillies, business owners, and just normal working class people. Most people from bad neighbourhoods aren't dangerous. The police that hang around those neighbourhoods are more of a threat to your safety than the people who live in them.