The problem with LA and tourist traps is that locals go to the same places as the tourist do such as

Hollywood
Beverly Hills
Santa Monica
The museums
Disneyland
Various beaches
Universal Studios
Griffith Park


I can't think of any place that only tourist go to but all of the above are busy
with tourist

Bad areas: There are good and bad areas back to back as mentioned above generally if you see bars on the windows of homes you know it is a bad area. If you stay on the freeway to get to one place or another and just know where you need to exit you will be fine. It is when you get off the freeway for gas or directions and find yourself where you shouldn't.