When we say "gay culture" we usually mean the most visible element or social expression of homosexual identity typified by Gay Pride parades, or events like the Folsom Street Fair. These events are flamboyant affairs with lots of costumes, cross-dressing and overt eroticism. Outrageous appearances, and behavior are normal in this context. If you don't like leather and chains and lots of nudity you won't like this scene.
Gay culture also has its own vocabulary: "bear", "twink", "top", "bottom" etc... There are very specific labels for each role in the community relating to appearance, sexual tastes, and attitude.
Many people find this stuff offensive. Conservatives point at a picture of a scantily clad transvestite on a float at a parade as more evidence that homosexuality is sinful, but there are a number of reasons to reject that idea:
- At base it is an aesthetic judgment. So, some people find it scandalous. So what? That is personal taste. What, exactly, is wrong with a little leather?
- The key word in the phrase gay culture is culture. Even if there is behavior you find distasteful or immoral it is not central to being homosexual. One does not have to be effeminate to be a gay man, or butch to be a lesbian.
- Not all homosexuals participate in the popular variety of gay culture described here. The behavior of some cannot be attributed to all.
In fact, it's not surprising that gay culture is shocking to mainstream sensibilities. It is a subculture, like being "punk" or "goth", which exists in large part as an ongoing critique of the mainstream. It is SUPPOSED to offend you. It is part of creating a sense of community among those who get the rough end of the status quo stick. The slang, the dress code, the wild behavior - it is designed to create identity, by affirming membership in a social group.
Really, given the options out there, I think gay culture is pretty positive. Rather than a constant expression of rage (punk), or depression (goth), it is a merry farce lampooning the mainstream. It relieves the stress of being an outcast community with humor instead of resentment.