In our many trips to Disney, we've only encountered 3 rude CMs- and 2 were actually on the same ride but on different days.
We had an AWFUL bellman at the POLY (when we were staying CL for a week no less). I called for help with the bags when we were checking out. Having worked in the restaurant business all through college, I am a big tipper and I go out-of-my-way to be nice to EVERYONE. He showed up and I was zipping the last of our clothes into a hang-up bag. He said "you should not have called if you weren't ready" and he STORMED out of the room. I literally ran after him explaining that the suitcases and bags were all packed and in the 15 seconds it was going to take him to load them on the cart, I would have the hang up bag zipped up. (I realize this sounds like I'm exaggerating - I'm not!) He completely ignored me and left. Still not believing this had happened, I called the bell staff and asked for another bellman and explained what happened with the first. They apologized and but said the hotel was busy and that they didn't have time to wait for guests to pack. Ok, I agree but he wasn't waiting. We were ready to walk out of the room. Whatever...They sent up a WONDERFUL older bellman who I tipped $20 for less than 10 bags and just HOPED he told meanie CM what he missed for those 15 seconds!
Our other 2 unpleasant CMs were both on Test Track. What is it with that ride? Just as we were about to get on the ride, my DD5 (who loves TOT and roller coasters) decided she did not want to ride. Never mind that we had just waited an hour...I don't belive in forcing kids to ride anything (although secretly and temporarily wanting to kill them for making you wait in line and then backing out is acceptable

LOL). Anyway, I quickly asked a young female CM if DH and I could "child swap" and I could ride when DH got off. She and an older male CM both smiled and said sure - just to cross over the bridge and tell the CM on that side what happened and they would load me as a single. Great. I go across the track over the bridge and am told by a very rude CM to leave. I try and explain and he asked if they gave me a pass. No - I've never done this and didn't know I needed a pass but the CMs who told me are right there - pointed across track. He said he did not care what they told me, I can't do that and to leave.
Final other rude CM was on the GM virtual things you sit in coming off the ride. He YELLED at a young couple for going under (not touching) the rails put up to snake people through in a line (no one was in line and they were just trying to cut their walk). I didn't see that what they were doing was hurting anything or anyone but even assuming it was, the CM needed better manners! Had he yelled at my child for doing that I WOULD HAVE GONE OFF!!! (and I am typically a calm, positive person).
Thank you for letting me vent - I knew you DISers would understand and still love WDW. All of that being said, those are the only 3 of the hundreds of CMs I've come across in my years visiting WDW. The VAST MAJORITY are WONDERFUL and make the Disney experience so magical. I make a point to try and speak to a manager about any CM who goes out of their way to do something nice! Thanks to the 99.99% of the CMs who make Disney the most magical place in the World!!!

You are the reason we keep coming back!