On 20 Nov 2007 21:27:32 GMT, James Robinson wrote in
:

I know of a person who owns a Mercedes diesel who was pulled over by a
revenue officer to check that he wasn't using dyed fuel in his car. The
officer got a sample of fuel, and put a test chemical in that enhances
the dye as a check. When he confirmed the fuel was legal, he sent my
friend on his way. It shows they do check in some states.

It also proves that, without probable cause nor a warrant, the LEOs is
some states have no issue violating the fourth Constitutional
amendment guaranteeing against unreasonable search.