In lieu of a plugin, I always paste into a plain text editor and copy the stuff I actually want from there. I've always done this, not because of dark-patterny stuff, but just fonts and having bad aim with my cursor when I copy.
How about a Chrome plugin to disable Chrome's _own_ what-you-see-is-not-what-you-get behavior?
I occasionally find it convenient to select hostnames out of a URL in the address bar and paste them into a terminal. Chrome "helpfully" prepends noise to the text you actually copied ("scheme://"), which makes this a PITA.
as mentioned by others, on firefox you can set dom.event.clipboardevents.enabled to false in about:config, which prevents sites from being notified when you tried to copy something.