I generally only put people on my ignore list if they do dumb shit that messes up the functionality of the board. It's especially annoying when they do that for no reason other than to entertain themselves.
For Instance, I noticed bluzman61 moving company LLC decided to rearrange the music section to their own personal liking and bury everything else. So, he went on ignore and now the music section is back the way it was for me. Because, you know, once they figure out they're gonna get away with it on a technicality, they're gonna keep on doing it just for the fun of it. Bad element, those types.
Stupid thread titles are another pet peeve, those idiots go on ignore. The ones who do it all the time, anyway. If I can't tell what the thread is about by reading the title, and the same person is always doing dumb shit like that, they go on ignore.
There's a couple other instances of when I'd do that but I forget em at the moment.
After a week or so of being on the ignore list you kind of forget those people even exist.
Oh, another thing, people who always post a link in an op and then you have to click that link and then four more links to find the story. And then when you do finally do get to the story, it's stupid shit. Ainobody got time fo dat. Off to ignore for them, too, if they make a habit of it.
Can't recall ever putting someone on ignore because of their views.