Regarding the mumbling, it's not just actors who are guilty of this. I find that many young people do it routinely. The majority of people who have customer service positions or other jobs where they deal with the public a lot over the phone are younger and do NOT speak clearly. When I ask them to speak up they then YELL. No, no, no. Sometimes I'll ask them to adjust their headset. That helps. It's also a subtle reminder to them that they need to take responsibility for their side of the dialogue and I'm not just some deaf old lady.
I feel that business communications training is in order. Quite a bit, actually. Perhaps courtesy could be covered as well. Whenever I speak to someone over the phone who's courteous, business-like, and speaks clearly, I always assume they're over 40. When I meet them in person--if I do--that impression is usually proven to be correct.
