What mistakes make coconut rum vodka liqueur oily, bitter or flat?

Expanded Explanation

The most common mistake is using old or poorly prepared coconut. Fresh coconut should smell clean, sweet and slightly milky, not sour or musty. Brown skin can be removed for a cleaner flavour, although leaving a little on may add rustic depth. Coconut pieces should be cut small enough for extraction but not blended into a paste, which can make filtration difficult and create a cloudy, oily finish.

Bitterness usually comes from lime pith, over-crushed cardamom or excessive spice contact. Lime zest should be thin, with only the green outer layer. Cardamom pods should be lightly cracked, not ground, because ground cardamom releases quickly and is hard to filter. Too much vanilla can also make the drink feel heavy and sweet even before sugar is added.

Flatness often comes from weak coconut extraction or adding lime juice too early. Lime juice is best stirred in after filtration, where it brightens the finished liqueur rather than sitting in the jar for weeks. Proper filtering, patient resting and balanced sweetness are what turn the infusion from a rough coconut alcohol into a polished liqueur.