I'll wear my shoes in the entryway, kitchen, or any flooring that does not have carpet. I'd rather not wear shoes on carpet because of dirt. Most people follow my lead if they're coming into my house... but I don't make a big deal of it regardless. If they don't, I'll vacuum and be done with it. I'm not going to stop them unless their shoes are obviously covered in mud and etc.
My sister and her husband are anal-retentive about this. The only place in their house that isn't carpeted is the linoleum floor square - no more than 3 sq ft - across which the front door swings. As a result, you have to "hug the door" to stay on that piece if you attempt to close the door (or open the door) while still wearing shoes. And if you step on the carpet with your shoes, then you might as well have pulled a gun out of your pocket, loaded it, aimed it, and started a countdown, because they'll be ready to either tackle you or shoot you. Not kidding.
I can't stand people who are so pissy about their flooring.