I have never read in the bible whether eating of unclean meat as described in the Old Testament where it is allowed to eat "unclean meat" or unclean meat is now clean meat.
Except for one vision from Peter where the vision orders him to "eat unclean meat" however, this is clearly not literal as the context is for Peter to preach unto the Gentiles:
Acts 10:
(17) While Peter was wondering about the meaning of the vision, the men sent by Cornelius found out where Simon’s house was and stopped at the gate. (18) They called out, asking if Simon who was known as Peter was staying there.
(22) The men replied, “We have come from Cornelius the centurion. He is a righteous and God-fearing man, who is respected by all the Jewish people. A holy angel told him to ask you to come to his house so that he could hear what you have to say.” (23) Then Peter invited the men into the house to be his guests.
Other verses in the bible tells "all foods are clean" however we should take note that it says nothing about "all meats are clean", food is totally different word from meat.
Was the vision literal or not? If its literal what is the biblical proof? Why are people lead into concluding that this vision is to be taken literally?
UPDATE:
And what could be it's relation to Isaiah 66:17 which states:
Those who sanctify themselves and purify themselves, To go to the gardens After an idol in the midst, Eating swine’s flesh and the abomination and the mouse, Shall be consumed together,” says the LORD. (NKJV)
Which by deduction swine flesh as described in this verse refers to unclean meat, and the verse says, those who eat these Shall be consumed together which by deduction again means, AFAIK, refers to the end of the world. So in other words, those who consume unclean meat shall perish together in the end of the world, which basically puts the interpretation of Acts 10:17-118, 22-23 in question:
"It's okay to eat unclean meat as interpreted in the vision but doing so will cause you perish in the end" -- a questionable argument.