BonkEnc doesn't add its uninstaller to the Add/Remove Programs list, and manually running the uninstaller results in "This application has failed to start because smooth.dll was not found. Re-installing the application may fix this problem."
Now, it's understandable that the uninstaller doesn't receive a lot of attention- who would want to uninstall this great app? (I only was looking for that because I wondered whether I should uninstall the old version before installing the newest version.) But this seems like it'd be worth looking into.