What the staff are doing now is just fine with me. When a bot posts, it can easily be recognized as a bot most of the time and they deal with it.
I've little doubt in my mind that bots make up the majority of most vBulletin forum populations, so weeding through them to find every last
one would be a near impossible task. But hardly any of them ever post. Example,
search for members with the gamertag "USA". There will be
tons. Many of them have never posted and haven't even been around in ages, they have done no harm except drain some resources. Banning them now would have no effect.