I have more news to report
Different Gear Slots Have Very Different Kadala Success Rates
Conclusion: The Kadala Buff has been applied to some, but not all, gear slots.
Method
I tracked the following Kadala gambling. (In addition to my original post)
Boots
1054 “Kadala Trials”
92 Kadala drops
8.73% = Observed Success Rate
Gloves
692 “Kadala Trials”
130 Kadala drops
18.79% = Observed Success Rate
Chest Pieces
515 “Kadala Trials”
50 Kadala drops
9.71% = Observed Success Rate
95% Confidence Intervals
For each gear slot, lets estimate 95% Confidence Interval for its “Kadala Success Rate”.
Boots
8.73% = Observed Success Rate
0.87% = Standard Deviation
95% Confidence Interval for "Boot-specific Kadala Success Rate"
8.73% plus/minus 1.7%
7.03% to 10.43%
Gloves
18.79% = Observed Success Rate
1.48% = Standard Deviation
95% Confidence Interval for "Glove-specific Kadala Success Rate"
18.79% plus/minus 2.91%
15.883% to 21.7%
Chest Pieces
9.71% = Observed Success Rate
1.89% = Standard Deviation
95% Confidence Interval for "Chest-specific Kadala Success Rate"
9.71% plus/minus 3.71%
6.00% to 13.42%
Kadala is bugged … but its predictable and repeatable.