Also, how is it that it's possible to submit a quote with impossible characters to type? There should only be certain typeable characters that are allowed in keyhero quotes.

actually, if enough people down-vote it, it will get removed. Somewhere it says what the number is, below 2.5 or 2.0, I forget. But once something gets a bunch of ratings it is pretty hard to drive it down. This had 98 ratings and a score of 3.3 (rounded) and now I gave it a down and it is 3.3009708737864076 (not rounded).

Yes, and if you do that, absolutely nothing happens. You will still get that quote in the future.