To find out where/when you lose reputation on a post, you have to either write your own reputation manager that parses the user nodes info xml generator or use one that someone else has written.

As to why people should have to comment on why they downvote, if there were a field you had to fill out, I would just fill in each and every time "Because you suck!" Which is really helpful. Or else when I have posted the reason why I downvoted a node, my node gets heaps of rep and the "offending" node racks up far more loss of rep than I suspect would have happened had I not said anything. That's worse.

So I just keep the way I vote to myself. If I find something particularly wrong, I post a follow-up, but I don't downvote the node. Or else I send a /msg. That's usually enough to get things straightened up, or an admission of error. But sometimes you come across really dumb nodes and all you can do is -- them, and it's not even worth spending the time to explain why. Life is too short.

Posting a node is like hoeing up a rough stretch of barren ground, watering it, and planting some seeds. Sometimes you a rewarded by a flower, you gain XP and other people come along to and plant more flowers, and everything is peaceful and groovy and everyone gains a bucketload of rep.

But sometimes all you get is a weed.