Our church out here in New Mexico meets in a school and is pretty casual. Even so, we had our youth pastor filling in for our regular pastor. He wore a t-shirt (yikes) that had an alcohol related logo (double-yikes) and did not understand my consternation.
After explaining the concepts of respect and appropriateness, I eventually got through to him by explaining that clothing worn by ANYONE in church that is a distraction to the message and worship is doing Satan’s work by coming between the messenger of God and those who are to receive His word. That gave him pause.
Some of the people who have posted on this thread probably would not mind if folks showed up at church naked, and would say it is "judgmental" if anyone were to object.