A badge is not a monitoring device and a watch is not forced one you. You wear it voluntarily. Its not that monitoring employees is wrong, but there's a way to go about it. You can't force spy devices on a person's body or close to them constantly and win the approval/loyalty of your workers.

Why not install CCTV in the loo while you're at it? Staying inordinately long in there is also a form of slacking. How about microphone to monitor the conversation between workers?