Reading people's emotions from their outward appearance is hard.
Some people can get all hand-wavey and excited without actually being much higher than their baseline arousal level. When they're feeling down, you can tell that they're feeling down, and when they're excited, you feel like you're in the presence of a hurricane.
Others are the exact opposite, and can suck up a lot of flak before exploding (different people "explode" differently, but that's for another post).
We need this sort of diversity. The only danger is in trying to impose your internal baseline and personal standards upon the reactions of others; either agree to agree, or agree to disagree.