Paul and Purusothaman.
I have 5 Oxwall sites and many more other sites builted on Joomla and Concrete5. I have nearly no problems with spams on the J and C sites as I have with some of my Oxwall sites. They are effectively using a script-robot system to detect Oxwall sites very easely thus and also giving a false visitors number within the stats of the sites.
For sure ""the custom "field" does work"", but why should we have to rely on this effort?
I think the Oxwall team should look carefully into these problems while there is already five pages of discussions related to it.
My 2 cents.