That's a tough question to answer.
Firstly, "Bad" is a relative term...the sound I like may be very different to the sound you like.
All woods give a different sound. Agathis is not the most common of woods, and if I am correct, all Agathis now used comes from large planatations and the wood has been almost logged to extinction apart from these man-cultivated plantations.
I have never owned an agathis guitar, but if I recall it has a tone similar to mahog, which is rather fat, with an emphasis on lower mids.
I may be wrong though, I just recall having read that somewhere.
If you're really keen to fond out what sound you can expect from an agathis body, I'm sure there are many sites on the net with descriptions of the tonal characterstics of many woods.
try searching for "tone woods" on google, or perhaps someone here can give you a link to a site.
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