There are kind witness but on the whole, if a good deed is done its because they have to SHOW they are for 2 reasons
1. If the person they are helping knows they are a JW, they must give a "good witness"
2If the person is a stranger they have to let them them know they are a JW so it give them "a good witness"
It has nothing to do with helping or loving your neighbour, although when our a Dub you dont understand the difference.