In my experience, any candle can give off soot if not wicked correctly and/or burned correctly. However, I do think soy is cleaner burning in general, as long as the candle's wicked correctly and burned correctly (out of a draft, keep wick trimmed, etc.) ETA: I get good throw from my soy candles, but it takes a little longer for soy to "get going" and get that scent out into the room sometimes. My paraffin candles seem to zip that scent right out into the room a bit faster. And yes, as was posted before, some scents which will throw great in paraffin refuse to throw in soy. You just have to test. HTH!