Businesses are free to refuse service to anyone unless the snubbed customer is part of a protected class and they're being refused service because of their membership in that class.

So, you could refuse service to a woman because you don't like the way she treats her animals, but you couldn't refuse service to her because she's a woman.

You can refuse service based on WHAT someone does (or might do) but not WHO they are. Public accomodation covers the WHO.

If a person is loud, vulgar, drunk, threatening or wears or projects a message (say, swastika tattoos) that might offend or create problems for your customers or your image then you can refuse service.

Yes I know that swastikas are part of several cultures and have many different meanings but I used it as an example because most people equate it with Nazism. Use a racist t-shirt for a replacement in that example.

You CAN NOT refuse service based on race, religion, etc etc etc

You CAN refuse service for anything else...being an asshole, disrupting, not paying on time, etc etc etc

of the separation of church and state. I oppose state sanction discrimination.

A few decades back, religion was used to deny marriage to mixed race couples.

Religion is supposed to be a personal expression. A business exists in the public, it is sanctioned by the government and must follow tax laws unique to a business.

If people want to work in public space, they should not discriminate on the bases of race, gender, or sexual orientation.

If a customer is being an asshole, I think that is different.

...so long as it is not an impermissible reason.

Behavior wise by the owner of a business?

Maybe I don't like people in flip flops or tank tops because I don't want other patrons having to see pit hair and toe jam.
Maybe I don't like people that talk too loudly and disturb others.
Maybe I don't like people with Confederate flags or rainbow flags on their T-shirts.

So long as it isn't an issue of discriminating against a protected class, and as long as I'm consistent, it doesn't matter.

I've always wondered growing up and seeing The Sign - 'We reserve the right to refuse service to anyone'.

There are reasons that are categorically off limits - typically race, color, religion, or national origin. State law can enlarge that list, but it is the "top tier" of "no, you can't do that." Gender and disability may have some limiting considerations - e.g. I can't join Curves, and don't have to rent cars to the blind.

Whether sexual orientation is, or is not, in a "prohibited reason" category depends on state law. That's why you see these duels between bills in state legislatures to either expand an odd notion of "religious freedom" versus bills to include sexual orientation as a protected class in employment, housing or public accommodation.

But, no, if you don't like people who wear red shirts, out the door they go.

We decide on the rules for the kind of society we want. Under federal law, it's unlawful to discriminate on the basis of race, color, religion, national origin, age, and sex. Other protected classes include pregnancy, disability status, and veterans status.

To my knowledge, sexual orientation isn't a protected class, and discrimination would be legal, if morally wrong, in housing, employment, commerce, etc.

Of course there's a risk that some people will try to abuse anti-discrimination laws, but I think think false claims of discrimination usually fail in the end.

It's like a friend of mine who fired a chef when he found him in the restaurant after hours having sex in the dining room. The chef, who was French, filed a discrimination suit on the basis on national origin. My friend argued that, no, the chef wasn't fired because he was French, he was fired for having sex in the dining room. The judge agreed with my friend.

... or no reason at all.

If there are laws in place that restrict your right to do so, they are most likely structured around protected classes. That is to say, you could still refuse service to customers, provided this refusal is not based solely on their being part of a protected class.

My gaydar sucks. I mostly think guys are gay when they aren't. And I could care less as long as they are nice people.

But there are some real wackos out there and I try to weed them out as quickly as possible.

No shirt. No Shoes. No service.

Or if there is a health or safety issue.

Basically, I think the difference is BEHAVIOR versus who they ARE.

as a health hazard. She has a hard time finding anyone to fix stuff. They come once and then she never hears from them again.

I told her I didn't think any repair person would have to service stuff someplace that is a health hazard.

Exposing themselves to unrelated dangers was not part of the contract.

I'm a graphic designer and I have turned down jobs from companies I don't like.