@Sonaldo a "bad ending" doesn't make the journey useless. It's entertainment, not a walk of self-discovery.
If i could laugh, be enthralled in drama, or just enjoy cute pictures for 99% of the work, one-two chapters at the end doesn't negate that enjoyment from before. Not unless it completely re-contextuslizes the story (which it rarely does, despite feelings from those spurned). So the mystery genre is really the only genre to consistently need a good ending.
also sound like you are just biased against harems for personal reasons too. agree to disagree. I enjoy them more than not. You can't please everyone.