Dirty curb on a sidewalk

In Philippians 3:8, the apostle Paul compares his religious credentials to knowing Jesus. The difference could hardly be more emphatic: knowing Christ Jesus my Lord is of surpassing value, but Pauls past success is like 虜畚士歌盈士 (skubala). 虜畚士歌盈士 is commonly translated as rubbish, refuse, or garbage, but sometimes more strongly as dung, in both ancient and modern translations (Vulgate, Tyndale, KJV, NET). Some have suggested another four-letter translation, stronger than dung.

While teaching Greek, I used to say that 虜畚士歌盈士 is the closest thing to a swear word you can find in the New Testament - and I was repeating something that I had heard or read quite a few times. C. Spicq's Greek lexicon even suggests that 虜畚士歌盈士 should be rendered crap. But is it true? Is 虜畚士歌盈士 a swear word, or maybe a rude word? Or is it unobjectionable?
We have to define swear words to know if Paul used any. Swear words are often used as interjections (drat!), insults (that dratted child!) or invective curses (curse you, Perry the Platypus!). In general, swear words have synonyms that are acceptable for normal use like dung in place of the s-word. But unlike drat or dung, a real swear word is one that you wont use around your mother (to use a technical linguistic definition of profanity). They are not used in polite society.
With that in mind, I did a search of two exhaustive databases of ancient Greek literature (Perseus and Thesaurus Linguae Graecae) to see if 虜畚士歌盈士 functions as a swear word in Greek. I discovered that nowhere in all of ancient Greek literature is there a clear example of 虜畚士歌盈士 functioning as a swear word or even as a rude word. I could not find a single place where it was used as an insult, invective curse or interjection. In fact, the normal use of 虜畚士歌盈士 in ancient Greek scholarly literature makes it almost impossible that it was a swear word. Here is the evidence for my claim, a list of the known uses of 虜硫留了留 in ancient Greek texts.
  • Medical texts: Aretaeus the Cappadocian (1st century AD), Soranus (1st/2nd century AD), Galen (2nd century AD) and others: When describing disease symptoms, ancient doctors sometimes mention the condition of a patients feces (虜硫留了留). For example, Aretaeus says that jaundice is often accompanied by 虜硫留了留 that is white and clayey. (De caus. 1.15.2, 2.9; De cur. 2.5.4; De comp. 13.4; De rem.14.1; De aff. 19.2; similarly Artemidorus the Diviner, Onir. 1.67.11, 2.14.37)
  • Strabo, a geographer (1st century AD): Smyrnas streets lack proper drainage, so that when it rains, the filth (虜硫留了留) lies on the surface of the streets. (Geog.14.1.38)
  • Josephus, a historian (1st century AD): At the siege of Jerusalem, starvation was so severe that some people went to search the common sewers and old dunghills of cattle, and to eat the dung (虜硫留了留). (Wars 5.571)
  • Plutarch, a philosopher (1st century AD): Priests avoid touching excrement (虜硫留了留) and things left over from food because such things are neither pure nor clean. (De Iside. 4). The lees (dead yeast and other particles) should be filtered out of wine, since it is essentially the refuse (虜硫留了留) of wine (Quaes. Conv. 6.7).
  • Philo, a Jewish philosopher (1st century AD): just as wheat is sifted to remove the chaff, so people must abandon the moral qualities that are not divine, which we must leave like refuse (虜硫留了留) (De Sacr. 1. 109). In typical Philo fashion, he suggests that the ark is an allegory for the human body, and that the door in the ark was for the purpose of expelling excrement (虜硫留了留). (Q. Gen. 2:6)
  • Ben Sirach, a Jewish sage (2nd century BC): In the shaking of a sieve, the husks surface; thus also does the refuse (虜硫留了留) of a man in his speech (Sir. 27:4)
  • Sybilline Oracles (uncertain date): Refugees of war are described as the refuse (虜硫留了留) of war (Syb. Or. 7:58, 11:185).
  • Greek Anthology (some 1st and 2nd century AD, some uncertain): Four rather light-hearted poems use 虜硫留了留 to describe inedible material left over from food, such as lobster shell (I.6.89), unripe grapes that have been chewed up and spit out (III.9.375), or fallen table scraps (I.6.302, 303). One poem uses 虜硫留了留 to describe the dry sweepings of trash. Two epitaphs (tombstone inscriptions) use 虜硫留了留 to describe human remains (II.7.276, II.7.382).
  • Church fathers (2nd-4th centuries AD): The church fathers used 虜硫留了留 dozens of times, but every occurrence seems to be a quotation of or allusion to Pauls use in Phil 3:8.
This list covers every significant use of 虜硫留了留 from ancient Greek literature up through the 3rd century AD. I also surveyed the uses for the next several centuries after that, and found no variation in the meaning or use of 虜硫留了留. Some important observations about 虜硫留了留 arise:
  • Since 虜硫留了留 was used in dignified scholarly works by doctors, historians, philosophers and sages, there was nothing objectionable about the word at all. Plutarchs use of the word in a high society piece about proper wine etiquette is strong evidence that this word was not regarded as impolite.
  • 虜硫留了留 can be translated as either dung or trash, depending on the context. The uses of 虜硫留了留 in the list above demonstrate that 虜硫留了留 could refer to either dung or to other worthless waste.
  • Paul was not alone in using 虜硫留了留 as a metaphor for something worthless in the moral or religious realm. Philo and Sirach both used 虜硫留了留 to describe undesirable qualities that should be abandoned. Pauls interesting, and somewhat different, use of the word is to say that his desirable religious credentials (circumcision, pedigree, Pharisaism, zeal, obedience to the Law) were 虜硫留了留 worthless waste in comparison to knowing Jesus (Phil 3:4-8).