I'm going to do just one more post here unless someone answers my previous points. I'll list meanings from my lexicons, and this will show that not one single lexicon considers the word skubalon to be taboo or vulgar. Note in particular that one lexicon, Louw-Nida, does not even list dung as a meaning!
The Fribergs' Analytical Lexicon of the Greek NT (my favorite): "anything that is to be treated as worthless and thrown out, translated according to the context dung, rubbish, garbage, offscouring" (accessed through Bibloi 8.0 software)
Louw-Nida: “worthless or unwanted material that is rejected and normally thrown out — ‘rubbish, litter, trash.’” (accessed through Bibloi 8.0 software)
BAGD: "refuse, rubbish, leavings, dirt, dung." It then gives the plural ta skubala as "specif. of human excrement" (p. 758). Note that Phil. 3:8 does not have the article, so to me it's a stretch to make it have to mean "dung."
Abbot-Smith: "refuse, especially dung" (p. 410)
Middle Liddell: "dung, filth, refuse. (Said to be derived from eV kunaV balein.)" (p. 641)
Thayer's (accessed through e-Sword 10.0.5 software) says, "1) any refuse, as the excrement of animals, offscourings, rubbish, dregs 1a) of things worthless and detestable"
Souter’s A Pocket Lexicon to the Greek NT: “sweepings, refuse, especially dirt, dung (popularly used of the human skeleton” (p. 237)
So, there is no evidence in the lexicons that the word must be translated "dung" in Philippians, and every evidence that "trash" or "rubbish" is an excellent translation.