Some of them definitely aren't bad, but I find a vast majority of them to be woefully ill-placed. Whether it's in dead ends, smack dabbed in other machines, obstructing your path, or are way too close to another gobblegum machine, making its placement useless.
ZC is such a high quality DLC, but these gobblegum spots make it feel like I'm playing a custom zombies version of it. Which is to say, people have no idea how to properly place machines within the map's layout.