I try to weld my dupe hammer carefully - honest I do. I'm well aware which tags I can use it in, and I do not agree that I need reminding when it's about to be used.
I do, however, sometimes wonder whether I've used it appropriately. I try to keep an eye on most questions where I've used it to keep an eye out for the OP (or someone else) commenting along the lines of "That's not a duplicate"/"That's not answering my question"/"You're an idiot" and sometimes I've just re-opened the question.
I wish there was some feedback loop in place like there is with questions/answers (and to a lesser extent, comments) where the community can be proactive in telling me I've been an idiot-with-a-dupe-hammer.
I wondered what people might think about some (or all) users being able to provide me with feedback when I dupe hammer. Perhaps something as simple as a "good call"/"bad call" button next to the close-as-dupe message.
There could be some feedback to the closer, such as >3 "bad call" and the user gets an inbox message along the lines of
3 users have indicated that they think your close as duplicate is incorrect.
Is this a useful feature, or pointless?