For me, trusted manufacturers are those who sell products and honour their order queues in a timely manner.
But the subboard is not only for you. The staff, mods and admins tend to stay away from judging who is trustworth and who is not, because
#1 its difficult (think: detect a long con before its too late)
#2 it would allow for manipulation
Each subboard needs administrative care. If noone is posting there its more work than benefit. The existing subboards can be scanned for posts regarding a certain manufacturer to judge the interest in their products (or lack of the same).