Even me! Yes I am still playing this game! I took one look at those mastery and went "that does nothing without luck," but tbh, after winning so many UV games with it, I feel that Scavenger is less of a Mastery and more of a Masterless build or Pistol/Rapid hybrid build that can actually get some use out of the useless uniques it finds.
What makes it so strong is what it doesn't block and what it encourages you to get. Intuition is probably one of the best things to go for, you really want Whizkid 2 anyway, and right as you'd reach Deimos Lab or Hell's Armory on UV, you can see if you'd want to use it and then either level up and take it, or delay it until you need it and get another level of SoB or SoG or Hellrunner or something.
You can get benefit out of old assemblies and modded weapons you're not going to use anymore. You can carry single early game mods in weapons where they're useful and then get those mods back later.
In my opinion, it's a better rapid mastery and pistol mastery than the Technician's own two masteries in those categories. In short games where you can't max out both SoB and SoG, Sharpshooter does pull ahead, but the difference is actually not very big, and Scavenger has the advantage of being able to ramp up into roughly the same power level while getting the things that Sharpshooter needs anyway, rather than being forced to plateau while it gets those things, and in Angel of 100, Scavenger is just straight up better even before you factor in the whole disassembly thing. Once you max out SoB and SoG, Scavenger does comparable to outright better DPS on average with single pistols. Yes, all of them. They fire at the same speed so let's just look at the damage numbers.
Basic pistol & Blaster: 2d4, average 5.
Sharpshooter: 5 + 8 =12.
Scavenger: 10 + 5 = 15.
P3 pistol: 2d7, average 8.
Sharpshooter: 14 + 5 = 19 vs
Scavenger: 8 + 10 = 18
Combat Pistol: 3d3, average 6.
Sharpshooter: 9 + 5 = 14.
Scavenger: 6 + 10 = 16.
P3 Combat Pistol & Trigun: 3d6, average 10.5
Sharpshooter: 18 + 5 = 23
Scavenger: 10.5 + 10 = 20.5
Grammaton Cleric Beretta:
2d6, average 7, or 1d8 avg 4.5 x3, or 1d7 avg 4 x6
Sharpshooter: 12 + 5 = (17) / 8 + 5 = 13 x3 = (39) / 7 + 5 = 12 x6 = (72)
Scavenger: 7 + 10 = (17) / 4.5 + 10 = 14.5 x3 = (43.5) / 4 + 10 = 14 x6 = (84)
Anti Freak Jackal: 5d3 average 10
Sharpshooter: 15+5 = 20
Scavenger:10+10 = 20
This is on top of Scavenger being able to use rapid weapons effectively and disassemble things. The only advantages Sharpshooter has is better Trigun numbers and being able to use melee with Berserker, and I don't think anybody's been doing that.
Don't forget that in normal games, you can go to The Wall/Containment Area and get a guaranteed missile launcher to disassemble, then go to City of Skulls and get another one. One time I got two Sniper Packs in Deimos Lab and made myself a S2B3 pistol and won the game easy.
There's things you can do with Scavenger even in normal games and it's more reliable than Sharpshooter. One of the best things is being able to open with Rapid weapons when they're stronger and then either close the game out with Rapids if you can make a nanomachic, or pivot into pistols if you find a good one. I would say Scavenger is the most slept on of all the masteries. Some people see its potential, but most just look at what it gives you and go "eh" without realizing what its lack of overly harsh blocks enables you to do while forcing you to get things you want anyway, and if you end up never needing it... then don't take it! Just skip the mastery and grab Dualgunner and profit! It can pivot into a Masterless build in an instant if it's not coming in handy!
