Pearlescent I found : Odds, Rare, not so Rare
Ok so that's what I found so Far with 5 characters. It seems some comes more often than others...
Weapons :
Tsunami : 9
Undertaker : 9
Pearl Aries : 2
Serpens : 3
Nemesis : 2
Jackal : 3
Avenger : 5
Stalker : 2
Bessie : 2
Shields :
Alacritious Rose : 5
Alacritious Oméga : 4
Hardened Ironclad : 2
None ! Even a +2TFRI does not bring them quicker or drop better version than without... It's about a 100 runs of Armory or Craw for the first one, then get 1 or 2 more in the next runs, whatever Character or Class Mod you choose to use. Craw and LvL61 Chests drops quite nice ones, but the only Cyan from the Drifters I got was a crappy Serpens (Thought that was the last time I farmed them and I won't make a test out of it LOL).
Details on where I found them :
http://borderlandsguide.com/forum/pearlescent-you-found-farming-crawmerax
http://borderlandsguide.com/forum/pearlescent-you-found-armory
http://borderlandsguide.com/forum/pearlescent-you-found-drifters
http://borderlandsguide.com/forum/pearlescent-you-found-elsewhere
And no, your weapon affinity does not help to find the Cyans that fits the most your character...
List Updated.

For now Undertaker and Tsunami seems to be the most common. Stalker and Bessie seems quite rare...
For the Shields the Alacritious Rose is the Big Winner...
Time Spent on Borderlands : 1700 Hours +