Ahh now that you mention it, makes sense why those modifiers aren't available on the AH filters for those objects.
Bloody hell, I might have to re-think how my system works then =\

I think the way to calculate max values is different, I wrote a post in "Items" forum section, describing how i understand it and it works.

Cloaks..
max ilvl possible for cloaks is 62
max Dex value from group Stats is 89 (http://d3inferno.com/affixes/DexVit_XI_Secondary.html)
max Dex value from group Dex is 89 (http://d3inferno.com/affixes/Dex_15_Secondary.html)

so 89+89 = 178 Dex, although i have seen on the GAH just 162 Dex before sockets

Yeah your understanding seems to be correct and consistent with many "max value" spreadsheets I've seen around.

Thanks a lot for your help though, and all that work you've put into this site!
It's a great wealth of information.

But that seems pretty close. For starters Cloaks don't drop that much. Then you need a Cloak with both those mods. Then you need perfect rolls. Then you need a Cloak that actually gets posted on the AH.

Given these restrictions and the smallish sample size for Cloaks, I wouldn't necessarily expect to find "perfect" Dex ones out there.

why do you only add the secondary affixes?

Primary dex affixes only spawn on gloves, boots, amulets, and weapons. (and followers)

As a result, those are the only items that can get the really high Dex values of 200+.