Funny how some maps like Scorpion missed LvL on the first pass around, even for a "known" mapper like Cardigan.

How do they end up getting submitted... someone just wanders by and says "oh hey this map in my collection isn't on LvL, better submit it"? 

Any map can be submitted so long as it is a "final" release. If you submit a map that is not your own and the author does not want the map reviewed it will be removed, but that is about all.

It is also recommend that you also submit a review along with your suggested map, but this is not a requirement.