In one of my classes we're doing student presentations, a few students each week. This past week there was one guy who said "umm..." in between each sentence and then 3 or 4 times within each sentence. After a while I couldn't help twitching every time he said it. I'm not even sure what his presentation was about by the end. Also, he never finished a single sentence - he would start one, and then think of something else to say and just stop in the middle of the first sentence to say whatever he just thought of, and then repeat the process until it was completely incomprehensible.
I think it takes some effort to graduate from college and take first-year moot court and whatever other classes and never absorb the most basic rule of public speaking: "don't keep saying UM."