Dinnertime is the one time I screen calls on the landline. Yes, even when it's Mom. She taught me the value of an uninterrupted dinner.
As for "always," for me, it's the classic: I get into the bathtub and the phone rings. Last week, I expected a call from my sister, so I brought the phone into the bathroom with me... and of course she called the cell phone, causing me to run all soapy and drippy through the apartment to find it. Okay, Fate, you win.
I'm such an OCD freak that it's not so much calling when I'm eating, but calling when I'm eating WITH MY HANDS. That means I've got put down the burrito/taco/egg roll and pick up the nasty, dirty cell phone that's been riding around in my pocket all day. And it's impossible to, say, wash your hands and continue eating and talking because if you're eating with your hands you've got to cradle the phone between your jaw and shoulder, and any chewing you do will be amplified to the point of obscuring any real communication.
And, yes, it seems to me that I'm MUCH more likely to get a phone call when I've just peeled away the tinfoil from my burrito and taken the first bite.