[This is long. Feel free to stop half way through, I wont know about it.]
I could have written Debodun's post myself, it's been my pet peeve for years, and I don't think it matters one bit whether the person talking is older, boring or repetitive -- interrupting, talking over, or turning away when someone is mid-sentence is RUDE. Maybe they don't know how hurtful it is, but it's the same as saying, "I think you're boring and unimportant."
I know I'm a good listener, everyone says so, and I've had to be because my husband is the most talkative man in the world. He comes home and starts telling me about his day while I'm fixing dinner and is still going without pause when dinner's over and I'm drying the last dish. He does taxes for people and I've heard about every single one of them, believe me all taxes are boring. So when he finally winds down and I get to tell him about my day and he turns and walks away in the middle of my first sentence -- it's aggravating.
It's also aggravating when I'm at the checkout line and I say, "How are you today?" and she says, "I have a headache," and I say, "Oh that's too bad, particularly since you have to work wi...." and by then she's turned away and started to chat with the bagger.
Yes, I've noticed that even when it's their choice of topic, some people don't want to listen to anything but their own voice.
I've listened to many a friend ramble on about the same old things or strangers in the store telling me about their car trouble. I don't mind one bit giving them a few minutes of my time. I don't have anything so important to do that it's worth hurting someone's feelings, so that I can hurry back to it. So don't tell me it's my fault for being boring, chances are your own conversation is not as scintillating as you think it is. That doesn't matter. It's an important part of our social fabric to listen to one another and give others a moment of our time.