I do not like to discourage showings. And with my Internet advertising, mailings and open houses... let's just say I get a lot of showings for my listings. However, any person seriously engaged in selling their home in Chicago knows what a pain it is to have the condo, house or two-flat ready for a showing. Owners usually have to leave the property during the showing as well. I recommend you leave. Mr. and Mrs. owner...Please leave during the showing. Thanks.
My point here is, I usually ask a few questions of the agent or potential buyer when they request a showing before I confirm an appointment. "Are you familiar with the area"?. "Is this an investor or will the buyer move into the property?". "Are you working with a mortgage broker?". "Do they need a big backyard or is a deck okay?".
If the buyer or agent is offended by a couple questions then they may not be serious or may not know what they are doing. In fact, they should ask those questions before making an appointment to show the property to clients.
If you were my client and I was selling your place... would you like me to ask a few serious questions before confirming the showing? Or, would you like to clean up, pack up and get out of your two-flat for someone who asks... "Oh, this is not a three flat?", when it is in fact a two flat. Says so on the listing.