Now, getting back to the OP. For me, libertarian ideals boil down to two simple principles.
1. Interactions, transactions, and relationships between people should be voluntary.
2. People shouldn't initiate force, or use the threat of force, against each other.
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So, let's apply those two principles to the OP about smoking in bars.
"I want to enter your bar and have a drink," the customer says.
"Fine," the owner says. "Come in. I'd like to make a profit off you."
"By the way, I also want a smoke-free environment," the customer says. "Make everybody inside put out their cigarettes."
"No. I don't want to do that."
"Well, I demand to have it that way."
"You're the customer. You don't get to dictate to me how I run my business. You have no right to give me orders; only requests."
"But I'm allergic to cigarette smoke!"
"Then go elsewhere," the owner says. "I'm not going to provide a smoke-free environment; I will never agree to do business with you under that condition. Please go away."
The appropriate thing for the customer to do is, of course, go away.
If a transaction is not voluntary, then the transaction shouldn't happen. It's simple. If both parties don't agree to the terms, then neither party should be forced into the exchange.
If one party tries to force the other into a disagreeable contract or transaction or relationship, then it's the government's role to step in and settle the dispute.
To sum it up, I've been to many bars and stores which had a sign on the wall: WE RESERVE THE RIGHT TO REFUSE SERVICE TO ANYONE. And that's fine. If you're obnoxious, or smelly, or dangerous-looking, or improperly dressed, or twitching and farting and screaming about Jesus at the top of your lungs, or otherwise unacceptable to the business owners, then they have the right to turn you away.
And, conversely, my friend said the other day, "I hate Walmart. I'm never shopping there." And that's just fine. Walmart certainly doesn't have the right to force her to come inside and spend her money. If she wants to go to K-Mart instead, Walmart certainly doesn't have the right to sue her, claiming she's unfairly discriminating against the Walton dynasty.