I think that for password, it's self explanatory if you have a chat up with a "lock" on it and the "clue" being the chat name.
If I was a GM I'd explain the rules (even if people kept spamming) and then whoever WANTS to participate and pay attention, can actually join the event, and all the spammers can be confused and just lose. I don't think that a few spammers should ruin it for the rest of the community.
As for events, just do random events. Sure people love Dice, H&S, and LMS, but a change from the GM's themselves would be lovely. For example, when announcing "Which event do you want" Give them choices: "Novice run, Password, H&S" and make them choose from those ONLY. You'll never get complains for LMS and Dice from most of the community, since they're already popular events. So just don't worry about them.