I have lost count of the amount of times i have personally hit a Royal Flush online and that does not include other players at my table also hitting the RF.
So it is safe to say that i have seen untold amounts of 'crazy' hands, over time they just become part of the game. Whether one wins the actual hand or not becomes less important and instead ones focus shifts towards gaining maximum value out of every hand.
For instance the last hand you posted was KK, a fine hand pre-flop. To then see a flop and connect with it so strongly, i would ill advise slowing down at this point instead i would head straight to value town. At that point in the hand, on the flop, you are behind to AA, AK and A7, AK is unlikely because you have two K's, so the probability that your opponent holds a strong hand such as any Ace (A2+) or even a pair himself are very strong if he starts calling your bets.
If at any point the opponent raises your bets then for sure there is a small chance he has you beat but i do not think i would fold, hardly ever. It would need an extremely reliable read on my opponent that he never re-raises me without the nuts to get me to lay down the value there.