What is the official and ethical stance on modifying dice? Obviously nothing huge, but let's says I took a nice black marker and filled in the usually white ink with black. What would you say about that if you saw it across the table?

...quoi?

I think dice are the only thing that I would absolutely not want to see modified in any way.

are we talking physical modifications or modification of dice results through upgrade cards?

because both should have rather obvious levels of tolerance from a given opponent ("**** no" and "no ****," respectively), so long as we know which one is being discussed

if you want special dice you got to earn them (or buy some on ebay)

I've seen a die where one of the hit symbols wasn't painted. It came like this out of the box. I mentioned to the player that he might want to add some white paint so that it would be visible to the people he's playing.

Outside of a circumstance like this, I don't think dice should be modified at all.

No. Modified dice can functionally change their use by adding weight to affect the roll.

I really would not like my opponent to use a dice he modifiers at all.

I recently painted all the icons on my dice silver (I tested black, but it's just not very visible). I did this because I have lost 2 dice while playing over this past year and I wasn't ever sure if I was the one who lost a die or if it was my opponent, however both times I got the short end of the stick and was the one who went home 1 die short. So I decided I was done with that, and painted my icons silver so I can tell my dice apart for my opponents' dice.

I figure if anything it ADDED an itty-bitty amount of weight to all the faces with icons, meaning I have a microscopically higher chance of rolling a blank now. If any of my opponents don't like that I am happy to put my dice away and share theirs for the game, or vice versa. But there is no way I am letting my dice get confused with my opponents dice again.