To me "Gospel culture" means things that we find acceptable or unacceptable that have no basis in doctrine or revelation. I have heard it said that it is official church policy any man holding a priesthood calling must always be clean shaven - while policy for SOME callings, it is not policy for all. But being clean shaven has become part of our culture and wearing a beard is no longer acceptable, especially for someone in authority.
Wearing hats is another example. 50 years ago a man would have been half naked without a hat, but today they are generally never worn. It has even become policy in our missions to not wear hats.
Gospel culture can also be seen in the way we pray. It's even taught in our primary lessons that we should pray in a specific format: greeting, gratitude, desires, closing. While this is all well and good, I doubt Joseph Smith ever said such a prayer. And how many times do you hear the opening "Dear Heavenly Father". It's almost mandatory. I've heard prayers started "Good morning, Father" and I totally endorse being personal with Him.
Another bit of Mormon culture is the "missionary fairwell" sacrament meeting. This has even been spoken agianst by general authorities yet it still happens. It's tradition to have a departing missionary and his/her family speak in sacrament, and heaven forbid even a prophet should try to change that! (notice the sarcasm?
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