I wanted to share my experience with a few different cups. So I've found at least two other posts remarking about the stench that comes from their melunas after barely 4-5 hours use. I've had a Ladycup, a Lunette, and the MINI SOFT MELUNA for a bit, and never had any problems with strong smells. The mini meluna would sometimes require slightly more scrubbing, but it would go away pretty quick. I thought I was safe.
So the mini meluna was great, and I was so impressed with the soft squishy cup and the ball end that I figured I'd order some bigger ones for my heavier days. I also figured they'd be essentially the same cup as my mini, just in a different shape. But it isn't!
I know they list their "main ingredient" as TPE, but I feel like they may have changed something in the new moulds when they released their new line.
I think the minis were/are still using the original line's materials. The inside of my soft mini is very smooth, and feels like silicone. It's REALLY squishy.
When I got my medium soft meluna, it wasn't the same at all. There was a mark along the rim (from the machine, apparently), the cup was stiffer, and the inside isn't smooth. When I run my finger around the inside of the cup, it feels rougher, and I think it has something to do with the material.
Long story short, my mini soft meluna is just fine. I took my medium meluna soft for a run today, and after a single use it smells. Like GOD AWFUL smells. I've tried wiping it down with rubbing alcohol and that seems to have helped it a bit, but I don't think I'll ever be using the damn thing again. I also have a small regular meluna, and I'm now afraid to even go near it.