Okay, assuming that the inspector can't tell the difference between C4 and a sprinkler part, why was this leaked to the media?
How about "we're evacuating the port of Miami for security concerns" instead of "we suspect C4 is at the port?" I'm starting to get the "boy who cried wolf" mentality about all these alerts, especially since they are generally end up as punchlines populating Jay Leno's monologue.
Eh, this happened multiple times with both Anthrax and Ricin.
Identifying substances accurately is really advanced-degree chemistry work in a lab - but you have all this equipment issued for field use now used by people that don't REALLY understand its capabilities.
Field anthrax tests test for substances that MIGHT be anthrax or MIGHT be ricin - and we saw false positives time after time, but also local agencies issuing press releases or giving press conferences that were leaving out the "might" and maybe."
Presumably this test simply test for nitrogen compounds, as virtually all explosives contain nitrogen compounds..however the users of the tests or spokesmen literally thought it was a test for "C4."