This is a little OT, in part because I can't think of any ONE time I've seen rude guests. Actually, having to say that makes me a little sad. Why treat someone as if they are your chattal or somehow less than you?
Anway, DH and I have started a little travel ritual when it comes to seeing the treatment service folks receive. To fully appreciate this, understand that I am, by nature, a bit of an Eeyore. You know how some people see the glass half full and some people see the glass as half empty? Well, I'm the person who's going around saying, "What flipping glass?" This dark outlook means I'm really sensitive to those people who are treated unfairly, even though I pretty much expect such things to happen. And it's really painful to see rude and inconsiderate behavior at Disney.
So, DH and I make it a point to fill out a a guest-services card (I can't remember what they're called officially) that praises a CM. We do one every day we're in Disney. Sometimes we pick someone we've interacted closely with, like when we've taken a really good tour or had a charismatic server. But we also keep an eye out for CMs who are being unfairly treated by other guests. When we choose the latter CM for praise, we first make sure to verbally commisserate with the CM at the time we see the offense. We will sometimes apologize on behalf of the larger Disney-guest community. Then, before we leave the park for the day, we take a couple of minutes to fill out the form and note how gracious the CM was under trying circumstances. To me, that's a real way of exceeding expectations because I've worked my fair share of guest-services/service positions and I know how hard it can be. And it always makes my day a little bit more magical to feel like I'm giving something back to those folks who work so hard for so little recognition and money.
There's also been more than once when I've attempted to diffuse a situation with my relatively odd sense of humor. Sometimes the strategy doesn't go over too well, though. It's funny how people who treat others as if they are personal servants don't like being asked to bus my tray. (They inevitably say, "I don't work here" and I inevitably respond "I know."

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