I started playing this game today; I was intrigued by the mechanic of building up cover whilst destroying tactical structures of the enemy, thus slowing them down and increasing our chances of winning the match.
Though apparently the servers I've visited have some unspoken rule about not destroying the enemies beautiful blocks, covering them mind you.
This raises the question, aren't constructions and such an activity done much better in Minecraft?
/rant
Anyways, are there more unspoken rules about what is griefing and what is not? to begin with I thought only friendly fire was considered such.

If someone gets mad at you for destroying the other teams structures they are a fag and should be called so. Destroying the other teams shit is good, do it.

Destroying your teams is not.

Sometimes I don't destroy it, I use it to my advantage >:).

Alright, Muncher, I shall remember your wise words and duck up the enemies stuff! Watch them cry, be banned/kicked, reset IP (Or something, I don't know how this works yet) rinse repeat.
Carebear tears taste so sweet...
Oh, don't get me wrong, I'd never teamkill (neither the buildings).

I hate it when some starts a votekick against someone who destroyed an enemy structure.

It's usually just buttmad children who cry over how their fort was broken.

Destroying other teams buildings is totally fine :) But often you ccan use them to your advantage and hide in them instead ^^

^Shotgun camping :D.