No. Goblin Sledder doesn't put a +1/+1 counter on it, it just gives the creature +1/+1 until end of turn. Also, if you try to target the scuzzback marauders with it, the ability will be countered because the persisted marauders aren't the same creature as the marauders you sacrificed.
Drat. Well, there's still:
BG
Tortured Existence + 2*Basking Rootwalla + Carrion Feeder: +1/+1 for {B}
Drat. Well, there's still:
BG
Tortured Existence + 2*Basking Rootwalla + Carrion Feeder: +1/+1 for {B}
&
B | R/G
Skirge Familiar + Stormscape Familiar OR Thunderscape Familiar + Gravescrabbler + Carrion Feeder: Infinite +1/+1
Or at least, I think so D: