At least when I worked in these environs, when one entered the White House or one of the associated buildings (Old Executive Office Building, etc.), one wasn't checked for drugs. If you had the right credentials, you went through a metal detector, and that was that.
sitetest
the locations i’ve worked would regularly search brief cases and backpacks. those were just DoD facilities.
if the secret service isn’t doing at least that for those that will be within range of the first family... they really aren’t providing much security at all.