Welcome - Do We Really Mean it?

On my morning walk today, I again spied several small flags and other signs in front of neighbors' homes that said variations of "Welcome". It got me thinking - do they really mean it? What if I went up to the door, knocked, and when someone came to the door, asked them if I could come in and get to know each other better.

You can see our previous home had a pottery figurine with such sign hanging from its mouth in the right center of the picture. I know I didn't, and still don't, want folks to just drop by. I expect it is the same with most others.