I can’t find my agent, or my agent is busy... will you show me a home?

Lately I've been struggling with trying to figure out why buyers work with agents that are not really working for them!  We happen to carry a fairly large listing inventory, so we receive a lot of sign calls.

We are continually asked to show homes to buyers that already have an agent.  Basically they say, I'm working with another agent, but would like you to do their job please!

Finally, I had to ask a lady today why she would work with someone that is not even available to show her homes.  Her response may surprise you, or maybe it won't.  She said, "we have an agreement that I will find the home & she will give me back 50% of the commission".  Don't even get me started. YIKES! 

Now, on the flip side - it's our job to represent our sellers best interest and do everything we can to expose their home to the absolute greatest number of buyers.  Therefore, we have been showing the homes.  But I have to admit, I really dislike sharing a commission with someone that wasn't even the PROCURING cause.

Your thoughts?