Winning isn't generally the point in a spar. You spar to sharpen your skills by employing them in an environment where you can have a reasonable assurance that you won't be intentionally, seriously injured, and have reasonably skilled peers that can help you to spot weak-points in your technique or tactics. Winning is for real fights and competition, but if you absolutely must know "who won" having a neutral observer declare a winner can work.
Touche'. While I find that genuine masters of a given art are usually pretty mellow, masters of a gym or training hall can get a little antsy if the idea that their style isn't awesome comes up. Many martial artists are prone to a bit of bravado.