Having been subjected to being spat at by the great unwashed numerous times in my current rols as a front line police officer and in my previous job as a prison officer, I know first hand how horrendous it can be and how it can affect you mentally. I have alsways said I would rather be punched than spat at, it's filthy plain and simple.
So it's nice to see that these are now being issued in a least one policing area and that they are compliant with human rights (and Geneva Convention - somethign about not reducing a person sensory perception).
In all honesty, this is the safest method of stopping someone from spitting for all involved, it's quick and a definite deterrant whilst not putting the officers in danger. From the perspective of the detained person spitting, yes it looks rediculous and hardly a wanted fashion accessory but also it means that they are not held on the floor in a prone position for any longer than is absolutely necessary (if at all) meeaning that there is a lower risk of positional asphyxiation and other medical complaints as a result of being put on the floor and the added stresses that adds to the body.
Surely this can only be a good thing and it makes me wonder why it has taken so long for them to be brought into use.