If you have a smoking wick, most of the time this is because the wick chosen for the candle is too big. When a wick is too big, it will try to consume more melted wax than the flame can efficiently burn. The unburned material breaks away as soot or smoke. If there is more fuel flowing up the wick than can be fully burned with the available oxygen, smoke is produced which is the evidence of the unburned fuel.
Mushrooming occurs when the wax in a candle burns faster than the wick, causing a curled, blackened bit of excess wick that does not burn properly and hangs like a charred ball over the candle. This is most common in highly scented candles. A little bit of mushrooming is okay, but excessive mushrooming can cause your candle to smoke and drip burnt pieces of wick into your melt pool.
The most common cause of mushrooming is using a wick that is too big for the candle. In order to rule out the wick as the problem, go down a size in wick on your next pour and try again.