
How thoroughly is luggage screened at Los Angeles Airport
It is pretty thorough on Los Angeles International Airport (LAX) and maybe all other airports in the US. All carry-on and check-in luggage not only go through x-ray screening but the TSA airport security also go through each baggage to check for security threats and risks.
They ban liquids, gels and aerosols and other items exceeding 3 ounces that are not packed in the zip-top bag are prohibited for the threat and risk these items may pose.
After the terrorist attack in the US, the TSA enhanced its security measures throughout the airport environment.
http://www.tsa.gov/travelers/airtravel/assistant/index.shtm#7

