This is always a hot topic around here!
No matter what you do, it's going to be the opposite of what someone else prefers, so you really can't win.
As a guest, I defer to the wishes of the host so if I were asked to remove my shoes I would (unless my socks or feet were unpresentable in which case I guess I would have to leave)
I do expect guests to wear shoes in my home. If someone walked into my house and took off their shoes without being asked to do so, I would find that very presumptuous!
If you are going to require shoelessness in your home, I wouldn't put up a sign...that just seems unfriendly. Businesses have signs, you know? You'll be shoeless yourself presumably, so that's a big hint. If you keep a pair of shoes at the door that's another hint. And if those hints fail, just politely ask them to take off the shoes. It might also be nice to have some clean socks handy in case people are uncomfortable being barefooted.
I would likely take my shoes off as I entered your house, and I'd hope that would be OK. If I bring a nice coffee cake, too would that help?
