What adverse secondary effects?

After doing some research on adverse secondary effects, it became clear to me that there really aren't any specific examples or strong numbers that help prove that these effects exist.  From what I have been able to gather, it looks like that the secondary-effects doctrine is nothing more than a way for government officials to try to get around the First Amendment and control the adult entertainment industry.  Just from looking at the , City of Renton v. Playtime Theatres, Inc., case, there didn't appear to be any need to develop zoning laws to control where these business would operate from.  By the look of it, besides from being having too small of a town where people were offended, nobody was robbed, raped, or caused disruptive behavior.  So why do we need this doctrine?

Now I'm not saying by any means that adult bookstores and strip clubs should be opening in within a few feet of schools or playgrounds, but after that, a line needs to be drawn.  I can understand the fear of opening such a business within a close proximity of a residential neighborhood for the fear of suspicious charters hanging around, but are we going to live in fear all the time? 

Let’s look at the alternative to allowing these businesses to open in scattered locations around cities and towns.  We could set a designated area in where all of the adult businesses operate, say just like Times Square pre-Giuliani.  Now we are going to have all of the rift raft gathered in one central location where nobody is going to want to visit.  Crime rates would rise in this designated area along with all the other adverse secondary effects.  Does that sound more appealing?  Just to try to sweep it under the rug.

Just because an adult bookstore or gentlemen's club opens doesn't mean that all hell is going to break loose in that area.  Actually, it's probably safe to say that some of the people fighting it during the day will be there later on at that night.  If there are any adverse secondary effects to be found, it's probably because of the zoning laws not because the lack of them.