Lol! The know-it-all customers even have a certain tone of voice you can identify immediately. Mine always start out with, "I just LOVE your site, it is SO impressive, you know SO much, I KNEW I wanted to talk to you..." and then they say all kinds of stupid stuff that shows they have no idea what they are talking about but they are so certain that they do. I will try a little to talk them out of something stupid and expensive, but if they show the slightest resistance, then I just say, "Okay" and feel like those guys in those old movies yes-dearing their wife while they read the paper. :)
There are lonely folks with enormous gobs of time on their hands who are determined to make even the most trivial phone call worth their while. Sometimes I get very interested in someone's life story. In my line of work, you get to hear some real doozies, I can tell you. But mostly people just want to gab about trivialities or worse, politics, which makes me want to puke. I just say, "I'd love to talk, but I have all this work I have to do..." It works.