Saw someone -2 2 on the scoreboard with ~30 points and decided to make this topic.
I think it will be more informative to have a separate value for how many penalty points you have accumulated. Right now, you can still be a spammer and TK a lot, and still have a decent score without anyone noticing. This should be accompanied by a message stating how many penalty points you earned from that action. It's difficult to figure out how much you are hurting your team, and this will be hard proof against those TWers.
There were times I TWd and did not realize it, and something like this would help me time my attacks better or choose which swings I use wisely. It is nice to know, especially since 'score' helps people see who is helping the team.
This would be similar to renown being switched between renown and infamy on the boards. The only problem is a matter of space and how it will look. Maybe it can be a score where numbers are separated by slashes like xx/-yy where xx is the points you accumulated or total score, and yy would be the amount of penalty points. (maybe a third number could be the total, but I'm sure we all could just subtract ourselves)
Future applications:
Once people generally approve the way the score system is run, reach a certain penalty level and you get a penalty on exp/gold. Something neat I read on here would be to pay for some of the upkeep on the teammates you hit, however I am not sure if that involves excessive calculations.