I think in addition to the danger of “seeing” immoral actions and being led into sin by sight of them, my main objection is more that we are not to touch the unclean thing. Christ did not frequent orgies because He would not grace an immoral revelry with His company, and neither should we. And yes, Christ ate with sinners - repentant sinners. On His terms.
I’m going to propose that you’re going too far, and here is why:
The Gospels don’t say the Lord ate with repentant sinners. It only says “sinners,” and his doing so did cause a scandal (because of course the Gospel cannot be referring only to alcohol consumption, since he would have been served wine in the home of a fully observant Jew of the time–they were not teetotallers):
“To what shall I compare this generation? It is like children who sit in marketplaces and call to one another, ‘We played the flute for you, but you did not dance, we sang a dirge but you did not mourn.’ For John came neither eating nor drinking, and they said, ‘He is possessed by a demon.’ The Son of Man came eating and drinking and they said, ‘Look, he is a glutton and a drunkard, a friend of tax collectors and sinners.’ But wisdom is vindicated by her works.” Matt. 11:16-19
Besides, St. Paul wrote about our question directly–that is, not the “unclean thing” but rather the “unclean person”:
*“I wrote you in my letter not to associate with immoral people, not at all referring to the immoral of this world or the greedy and robbers or idolaters; for you would then have to leave the world. But I now write to you not to associate with anyone named a brother, if he is immoral, greedy, an idolater, a slanderer, a drunkard, or a robber, not even to eat with such a person. For why should I be judging outsiders? Is it not your business to judge those within?” *
1 Cor. 5:9-12
So it is not our concern to be judging outsiders, but whether or not a venue a) is a near occasion of sin for us or those we socialize with and b) if by our patronage we are supporting what is explicitly and purposefully a near occasion for the general public.
We don’t have to leave the world–that is, we don’t have to seclude ourselves from those who go in for immoral things. We should choose friends whose association will be a spiritual help and not a temptation, but we don’t need to avoid every place where immoral people gather. We should not support a business whose raison d’être is to make money by seducing people into sin, but we do not have to boycott businesses who are legitimate but also count immoral people as their other patrons.
In the middle there is a grey area, and that is something to be considered on a case-by-case basis. It is worth thinking about whether we give tacit approval to the wrong thing by being at some club or other. Still, there is no blanket prohibition by which a Catholic may not socialize
in the same places that the openly immoral frequent, none at all. We must admonish fellow Christians who indulge in immoral things, and stay out of their society when they do, but we don’t have to take ourselves out of the world.