Google deletes them fairly quickly, at least the couple of times I heard of these things or removed them from friends'/colleagues' computers they were already gone from the Chrome Web Store. That Mozilla bug you linked in another comment reads like an awfully misguided application of policy.

One of these extensions I came across automatically closed about:extensions every time I opened it to prevent uninstallation. Eventually went through the chrome task manager, killing extensions one by one until I found the right one by trial and error. Very frustrating to debug.