Presets that can speed up your workflow with a simple 'click' of a mouse or tap on a touchpad or screen. Lightroom comes with them and you can make new ones and save them for future use easily. A google search for "Lightroom presets" results in over three million hits. That's a lot of hits. You can buy them, make them or use an add in program that essentially clicks your way to awesomeness.
There is nothing wrong or evil about them if they help you attain your vision. If you just randomly click them for discovery purposes that is ok too, but the real power is knowing what you want to accomplish and determining the best way to get there. Understanding how dodging and burning as well as sharpening, effects the eye would be a great starting point. Many folks suggest studying the master painters to see how they accomplished feeling as well as seeing with paint, brush and canvas. They had neither presets or filters (another topic for another time).
I was reminded of this while reading a passage in Clapton's Guitar contributed by George Gruhn...
Post processing is not unlike repairing a guitar in that you are trying to make your photograph look and feel like what you saw. The best post processing leaves your viewer admiring your photograph and wondering how you made it. If your photograph is distinctive, if you have put your heart and soul into it, it will be a better photograph. One that will stand the test of time, rather than simply what was once a popular trend achieved by a few clicks of your mouse.
The choice is yours.
See ya around,