When I listened to a lot of dark music, I was more inclined to sadness. There are a number of reasons for that, the most obvious being: 1) the direct negative spiritual influence, and 2) the general mental effect of listening to negative music - it makes you sad, too!
Another reason though, is more to do with the scene itself. The secular black metal scene often use anger and sadness as standards; the better you can express those emotions, the more positive reviews you will probably get.
When you're in a scene where there's a lot of competition to be the "darkest", most "pained" band out there, how do you think people in the scene are going to be?
Obviously very few people will want to exhibit those traits, but when you're around it so much, it rubs off on your psyche anyway! I guess you could say you sort of start "wanting" those emotions anyway. I'm not a psychology expert, but I would definitely describe it that way. And any secularists reading this will say how stupid these words are. "They don't want to be sad, the world just keeps dragging them down! They listen to that music to help them cope with their feelings! They listen to that music because it 'just sounds good'!" It's hard to imagine, but that's actually usually wrong.
Imagine you or your friends being "cheery" people, greeting each other with sincere smiles and hugs. It makes you cringe. Imagine dealing with the "preps" out there. Who would want to do that? But see, those people aren't like that just because they're on some euphoric popularity trip, or because they're "idiots", they're just different. Some of them are putting on a show, sure, but some of them are just happy people. There are plenty of happy people in the world who are very aware of what's going on. (What's "actually going on" is different from what the secular scene tells you too, but that's for another post.)
Happiness, true happiness, seems to be a sign of weakness in that scene, and in fact in a lot of the world in general. It's not! It's okay to be happy! Your sadness doesn't have to define you. You don't have to hide behind it. It's okay to look at the good in a situation. It's okay to be positive, even cheery if you feel like it, even if "it's faggy" / "it's douchey" / what have you, because it's not! Happiness, even being goofy is okay. It's fine to listen to happier music, too.
I would actually recommend it! The world is full of bad stuff, to be sure, but we don't have to let it affect us so much! We don't have to listen to music based on it and that revels in it. Finding more positive stuff will clean out your psyche (and even your spirit, depending how positive it is). Thinking more positively will magnify those effects.
I know how weird it is for a lot of metalheads to think this way, but try it! Express happiness! Happiness and sadness are contagious, which would you rather someone spread to you? Maybe you can become someone who starts it where you are.
Philippians 4:4 Rejoice in the Lord always: and again I say, Rejoice!
Psalms 32:11 Be glad in the LORD and rejoice, you righteous ones; And shout for joy, all you who are upright in heart.
Luke 1:47 And my spirit has rejoiced in God my Savior.
God bless and guide you all according to His perfect will! In Jesus' name, Amen.