Topic Beware guild bank theif
New members should never be given bank access for at least a month.
And I don't know if it was ever fixed, but there was a bug back in the day that would let the guild bank thief bypass guild rank restrictions unless you manually reset their guild rank, so when in doubt promote and then immediately demote again.
Anyone that wants to be in the guild for legit reasons won't mind waiting to get something as trivial as bank access. The ninjas will leave guild on the spot.