Whirlwind, I don't think there's one correct answer to your question (this may be why there haven't been any responses yet).
There will surely be some that might look at their winning percentage as a "badge of honor" and they will always try to make it higher.
I know a couple of players here that like to be one of the lower rated when joining a tournament. They prefer to play stronger players. So, their winning % will not be high.
My guess is that most players don't really care what their winning % is. Those that put a lot of effort into chess know that they can learn from a loss, and are probably not going to play those rated well below them.
I've been getting philosophical lately about people's reactions to winning and losing, whether in Chess or other games or sports (i.e., football, baseball, etc.).
Naturally, everybody loves to win games. Often times, the more we care about the game, the more we want to win.
I see a lot of chess players be really hard on themselves when they lose, even if only just one game. Some take losses harder than others.
Chess is a competitive game. It is not like, say, a video game, or a puzzle book.
Video games, crossword puzzles, logic problems, chess, baseball, and football all have the common requirement of practice in order for one to gain more skill in them. But video games and puzzles are examples of things that, with enough practice, one should be able to win (or solve) fairly consistently.
Chess, baseball, football, and other sports, however, pit one human entity against another. In these games, one cannot necessarily expect to win fairly consistently simply by practicing, because one's opponent is not constant or insentient--the opponent can practice, too.
Getting good enough at a video game may enable someone to beat it between 90 and 100% of the time, depending on the game. But if two people approximately equally skilled in chess play a series of games, each can be expected to win about 50% of the time--and lose about 50% of the time. Yet I see some people hold themselves to the same standard as if they were playing a video game. They seem to view chess as something they should eventually be able to master and win consistently--80, 90, or 100%. As a result, they set themselves up for disappointment and frustration.
Food for thought: a Major League Baseball team that wins 60% of its games over the course of a season is considered to be quite good and, generally, playoff-caliber. An MLB team that wins 70% of its games is considered exceptionally good and even record-setting. These numbers would be considered somewhat weaker by NFL teams. An NFL team that wins 60% of its games would probably be about 10-6, which is not bad, but perhaps not worthy of a Super Bowl appearance. Seventy percent (11-5) is only slightly better. Clearly, the threshold of adequacy depends on the game, among other things.
So I ask: what winning percentage, in your opinion, might be a good goal for a chess player? Is 50% good enough? Should he aim for 60 or 70%? Or is 40% or even lower acceptable?