One thing that seems to work really well, even down to how damage can manifest in combat, is to page the person you are about to do something to and tell them what you have planned, and work out the details of the attack. This is a good way to clear problems up before they arise, because even though you could ICly do something, there is the matter of respecting that the other player may have something else already planned or needing to be resolved first.

By discussing things ahead of time, most problems that might arise with invoking no-consent can be avoided. In some cases, a polite warning and discussion of powers before people jump to conclusions about what is going to happen to them next.

It should be noted, however, that complaining about someone using his or her power in an IC fashion is immature and ludicrous, because those people are playing those characters for a reason, and have been awarded those characters for reasons. Rather than complain, talk to the person and try to discuss what can be worked out.

Many players could technically go out and 'ruin' the MUX for other players' characters, and have every IC reason to do so, but should they? It is all a matter of balance and counterbalance. We are all here to have fun. There are reasons we do not do something to 'ruin' everyone else's plans, because they wouldn't like it if it was done to them. More often than not, there's going to be another way of handling something, and one that is more mutually acceptable. And at the same time, the player also has to realize that certain things will happen, and should be allowed to happen, because essentially choosing to ignore anything that isn't convenient for his/her character is just as selfish and harmful. Ideally it's a mutual understanding, and a mutual effort to maintain an intelligent balance.