I used to work for a developer in Saint Louis. They said their showing rate was high, and I estimate they showed one listing about 3-4 times per week. I'll link to their site so you can get an idea of the quality of the condo's, but you also have to take into consideration location (obviously). Really the best way to find an answer to this question is probably through a competitor. I don't think it would be morally wrong to pose as a prospective, and then ask your question once you've feigned interest in a listing.
Metropolis Condos St. Louis