The biggest drawback to the Hustler coils is the fact they are covered with vinyl plastic. Moisture gets under this cover and causes the resonant point to change.
I've heard of people placing them in an oven at low temperature for a few minutes, but you run the risk of melting the vinyl. Placing them under a 100 watt lamp is a little safer, but you have to make sure not to get them too hot. It takes several hours to "cook" out the moisture.