I've never been good with crystal balls. Like you, I get clouds and clouds and more clouds. And a big result of disappointment.
I'm more of a scryer of casted lots, tea leaves, and other things that actually move, change shape, etc. But I do scry on black surfaces occasionally. Transparent ones are less productive. I feel like I'm trying to peek into a room through a keyhole. I feel cramped being so confined to a see-thru sphere. Have you ever tried looking through a keyhole? It's annoying!
What isn't working isn't the ball, it's you. You can peer into a random still puddle in the street and scry. You need to work on your ability to scry which is reliant on clairvoyancy and the ability to let your intuition and creative side take over without allowing yourself to "think" about it. Basically as soon as you start analyzing and not just gazing like brain dead guppy, you're not going to get anything. Just relax and at first, don't even observe. When something shifts, just let it. Don't pay attention, just hold the mood. Later you can work on paying attention. If you already scry with other things, than maybe you are like me and just can't relate to the structure. Try something different. My favorite is a wide bowl, like a candy dish, with black coffee inside and a small round quartz crystal at the bottom of the liquid. I use the same technique as with crystal ball gazing and get way better results. Some people use ink but seriously? I'm not cleaning that up! What if it spills? No way! Coffee has magick properties and medicinal properties for mental stimulation so it has an added bonus. I drink a cup of my own on the side to join/connect with it like one would when working with herbs (and their spirit).