Here is my disclaimer. Like a musical artist who sings songs that are written by others and have even been performed by others, I preach some sermons (if I believe they are good ones) that have been written by others and originally preached by someone else. Other of these sermons may come from good articles that I thought should be preached. Regardless of the sources they are preached with my unique style and personality. Some may think this similar to plagiarism, but it is no different from someone who watches a TV cooking show and then follows the recipes to make the same meals. I don't pretend that all of the thoughts, ideas, phrases, titles, outlines, etc. that I preach are original to me.
The point of preaching is not to be original, but to teach truth. If someone has taught the truth in a good way, it needs to be reproduced. A man who cooked in the White House for the first President Bush and President Clinton later cooked at a camp where my wife and I were. He made some amazing brownies and my wife asked him for the recipe. Would it be wrong for her to use the recipe he gave her to make delicious brownies? Well, in fact the recipe was not his anyway. He showed her his secret recipe: a Ghirardelli box mix! He explained that they had spent years with experts coming up with the best combination, so why not make use of that effort.
I have some good ideas (and some duds) and am sure the same is true for other preachers. I share my good ideas and they share theirs and together we help make each other better.