Recently I updated my MacBook Pro to El Captain, and I don't like El Captain. One major thing I noticed is the screen went blurry. Text and everything. My Mac does not have retina display, and yet it looked fine when I still had Yosemite. Well, not saying Yosemite was good either, but it was at least better than El Captain. Found several solutions online but they didn't quite work for me. After digging into the settings, I found below method working for me to fix the blurry issue.
So I went to "System Preferences" > "Displays". And then I changed "Resolution" under the "Display" tag to "Scaled" and then switched several times among the choices (screen went dark and came back with larger/smaller text etc.) Then I switch back to "Default for display". And the screen is now clean and shiny. I had no idea why it works for me while other methods don't, but I expected it might be a bug? Not sure.
Below are the several methods mentioned online, just as a log.
Go to "System Preferences" > "Accessibility" > "Zoom", and uncheck "Smooth Images".
Run screen calibration by going to "System Preferences" > "Displays" > "Color". Then press Option key while pressing the "Calibrate" button. Go to the "Expert Mode" and follow the instructions.
Go to "System Preferences" > "General" and uncheck "Use LCD font smoothing when available"
Shame on you, Apple.