We often seen ones that are basically non-weighted - just something someone knocked together.
They droop, they fall over without any wind, they are more hassle than they are worth.
One team set up pylons exactly correct according to the rulebook with the 2" space between the ground and bottom (with a springy rod to hold it) and was told by one of our most experienced refs they had to go (because of the metal). No one had ever seen them here before.