How Much Security Do Security Checks Actually Give?

[ghosthunter]

Security checks do absolutely nothing except give more employment to people as "security guards".

You can have sticks of dynamite attached to a clock in your shopping bag and you will just walk right through the "security" inspection. That is already for an obvious "bomb"... what else for an improvised explosive device which can look like anything (example, 1L bottle of coke, a pocketbook, woman's shoulderbag)?