Is it moral to wear rings in the ears/have tattoos/unconventional haircuts/sexy clothes (like very short skirts) if the majority of people on the street don't like those things and they are bothered because of them? We will suppose the majority of your friends like those things or aren't bothered at all by them but the majority of unknown people are. I'm not talking about wearing them at job or at an official dinner, I'm talking about wearing them on the street. Wearing those things in the street may mean you don't respect other people but on the other hand being bothered that someone wears rings in the ears or wears something unconventional may mean you don't respect his preferences. From a moral standpoint which side is right? Does it matter what that unconventional thing is? (perhaps you consider tattoos acceptable but you don't feel the same way about sexy clothes) Again , his friends agree with she/him but the majority of people don't.

Based on a moral like 'do no harm', It's not necessarily harmful to judge a book by the cover. It is necessarily a partial view of perspective (only sees a part of the whole information available) and necessarily leads to opportunity for partial conclusions when left unconsidered. A partial view may lead to choices that do harm from the ignorance of not considering a more complete view of information.

Here is a paraphrasing of the OP:

When there is a difference between individual preferences within a population, whose preferences are correct? Is it based on majority rule?

According to the minimalist moral codes popular in liberal democracies, no it isn't morally wrong to do so - people are generally supposed to be tolerant of differences that don't harm other people. That being said, cultural norms almost always includes rules about how to dress and otherwise present yourself in public. Thus, how you dress will communicate some message about how you view yourself in relation to the prevailing cultural norms, and if you deviate too far away in how you dress, some people will suspect you also deviate in other more important matters.

Depends on who you ask. Clothes / forms of expression have been found immoral throughout the entirety of human civilization's history (and probably before that as well).

Even our democratic societies have a history of trying to legislate against such things. Jazz and rock'n'roll went through various attempts at legislative censorship from the 20s through the 60s, for example. And we still legislate against similar things. Look at Australia's harsh censorship laws regarding movies and computer games, or how nudism is regulated in many "western" countries. Other forms of governship have (as we all know) even harsher history of censorship and crackdown on "moral violations".

And it's still apparent in our culture. Women who dress "provocatively" are dubbed sluts, hipsters are ridiculed for being superficial, punks are seen as rabble... not everyone hold such opinions, but they are common enough. It's just our version of the same form of cultural censorship that seems to happen in pretty much any society. You even have a major political direction in the form of conservatism (conservatism can be other things as well, it's a broad term) , which at its core is a protest against "moral degradation".

Are there arguments against it? Yes. Societies that are more accepting towards broad freedom of expression tend to score better on overall tests of happiness. It seems that the minor discomfort of having to accept minor difference is less than the major discomforts caused by actively oppressing such differences.

So you can make a utilitarian argument that these forms of expression are, indeed, not immoral. Rather it is moral to accept them.