they will also hassle you if your car smokes.
they can give you crap about a fart cannon exhaust.
and they really like getting the punks driving 240's that are slammed on their balls so bad that they kick up busted reflectors as they change lanes.

But generally, they go after the truckers. Usually for dumb shit like accessory lights. But they do keep an eye out for crap stacked up that isn't secured properly, or if the trailer is overweight and squishing the tires down, stuff like that.
Personally, I treat them like any other law enforcement. Don't catch their attention and avoid them all together if at all possible.