Hi @bobv2 :)
I've never had any problems with my game breaking by downloading builds from the Exchange and not having stuff from the store or EP/SPs installed.
It will influence the aesthetics of the build of course but should not cause any corruption to your game.
So if you don't mind having a toilet appear on a patio instead of a hot tub for example ;) just enjoy picking, downloading and using lots you like the looks of ... there are some awesome builds about. (Good idea of yours to check them with custard though :) , as some bad CC can definitely cause undesired issues.)
