Irritating for screen sharing with people who use default putty settings, small size courier new, default colors. Ugh. Savages.
I'm visually impaired, so if I were to screen-share my PuTTY window, you'd be treated to 22-point bold Consolas and mostly white on black.
This points out, though, that for accessibility, frame-buffer sharing is really not ideal. What we really need is some kind of high-level content sharing, where the content is re-rendered on the viewer's machine with their settings.
I wish Git(Hub|Lab) READMEs could embed asciinema sessions instead of blurry, bulky, un-seekable GIF clips.
I had one where I had to change settings to keep any text with red from being a muddy mess.
They mostly don't even use good resampling algorithms either.