Why don;t you try telling your customers that it is your car shop so no whining about service, no comments, and no requests, no talking about subjects you don;t aprove of while they are waiting, etc because it is your house and you make the rules.
That's a perfectly viable way of doing business. For example, having a rule that you're not allowed to be belligerent to the staff is generally speaking, a non-official rule in a lot of places. There are actually signs about that in some places (hospitals for example).
You can't analogize an MMO game to anything in the real world, as it's vastly different from dealing with people and places in the real world. The closest thing to an appropriate analogy I can think of, is it's like email spam. Stuff coming over your ingame comms that's irrelevant and most likely not of interest to you. Would you prefer if your ISP didn't screen spam for you?
Vinkman- I disagree it's a better answer, though it does work reasonably well as long as there aren't too many people on about it. I personally see .squelch as being mainly used for people that just annoy you for whatever reason, but aren't breaking the rules. Now the rules are slightly nebulous, but if lack of common sense gets you muted, it's probably for a halfway decent reason. To have as company policy 'anything goes' on the public channels, and leaving people to weed out the BS every time they log in, IMO is a poor, poor decision.
Again, what does it accomplish, other than giving the loud obnoxious people a semi-captive audience?
Wiley.