Define Dexless

Dexless thieves don't exist. They all have at least 25 :O

In all seriousness. I thought this was a great way to classify different types of thieves:

Normal Dex: Uses regular equipment. Can use dex from equips to equip weapon, but also has luk scrolled equipment.
(This includes "low dex," which I think is a stupid classification. Why would you not take advantage of dex on your equips at all, especially since thieves can't scroll everything for their mainstat? Low dex thieves are normal dex.)
Dexless: Uses equipment that does not require dex. Has 25 base dex.
Min Dex: Uses regular weapons, but keeps base dex to a minimum and relies entirely on dex equipment to reach the dex requirement for their weapon.

I think the distinction of normal to low dex is that normal dex = uses all max level gear (mostly for looks and cause the build is easiest), low dex = uses optimal stats gear. If you're wearing a Pirate top+bottom with Mamba at 8x, that's normal dex. If you have a China bottom & Stud top and use the stats efficiently, low dex.

I'd say min dex is a bit restrictive, more like "maximizes dex boost from gear" cause the same as some stuff can only add dex, there is stuff (Zakum helm) that adds luk and cannot be converted to dex. Also, if you've got +125 dex (30 helm + 35 overall + 22 pendant + 15 shoe + 8 face + 15 earring is quite possible), you're not exactly gonna push for more dex. Might as well get some luk.

So in order of base dex, probably, normal dex - low dex - min dex - dexless.