As already pointed out, password checker has limited use if, as is most common with the spammers, the (unpassworded) rar contains another (passworded) archive.
Usenet is currently awash with such scams, and sad to say but by far the best way to manage this is to make sure that you only grab your NZBs from trusted sources. Only use the general (auto)indexers if you know what you're doing, since even with all their resources and ever more sophisticated attempts to filter out the spam, it's just been a game of whack-a-mole. Alt.Binz is not really going to be able to improve on these methods much, so if they get past the indexer checks, they're likely to get past Alt.Binz checks too.
Getting a lot of passworded stuff is a sure sign that you need to rethink your approach, IMHO ...