>>190
For the record your argument was that it
>simply means "common". Thus, this cannot be referring to overturning the Levitical food prohibitions!
So I explained how it's not only "common". It has been used to mean 'defiled' and 'profane' which are synonymous to 'unclean' however not the exact word as levitically 'unclean'. Are 'unclean' spirits 'unclean' levitically if their 'unclean' is expressed with the same term? This does not disprove your point but it's important to realize this word was not wholly reserved for levitical 'unclean'.
Meanings are decided by instances of use. That's how linguists deduce what possible meanings in target language include in dictionaries and lexicons. Under Thayer's Greek Lexicon you have:
"by the Jews opposed to ἅγιος, ἡγιασμένος, καθαρός; hence unhallowed, Latinprofanus, levitically unclean"
That means it has been used in context of antonym for katharos i.e. it can be understood as akatharos if context justifies that.

>But the verse that you say "overturns" the dietary laws specifically uses κοινός. Thus, it cannot be referring to the dietary laws.
If it cannot then how is it said in response to 'koinos or akatharos' without making separation? This is logical problem. 'Or' is inclusive. Both have to do with a state of impurity and can very well mean the same thing but second word added as a synonym (synonyms don't have exactly the same meaning) for fuller meaning or clarity's sake and that sort of use is even more clearer in chapter 20 of Dialogue with Trypho (http://www.newadvent.org/fathers/01282.htm ctrl+f common or unclean). If koinos and akatharos are to be separate subjects the response is lacking because it only addresses one part of utterance. If the vision is entirely metaphorical and has nothing to do with diet only people and akatharos people are still akatharos how come, since Christ died for all? You can argue metaphorical intention, I might even weakly agree, but then koinos here is synonymous with akatharos and you have to reject what Paul wrote about koinos food.
>but it's literally referring to DIRTY food
Back to Romans 14:14. Moreover do you remember what cropped up time after time when dealing with uncleanliness? Literal washing. Even the article you've linked doesn't say that koinos is literally dirty and that's all there's to it.
"In fact, you will notice that the term “common” [koinos] is also used in Mark 7:1, referring to the disciples’ dirty hands, because it was believed that dirt defiled their hands, and that this defilement would transfer to the individual if a person ate or drank with dirty (common) hands. "

>>191
The 'dirty' question is explained above.