THE ACFT WAS BEING FLOWN TO A UNI-DIRECTIONAL ARPT WITH AN INSTRUCTOR PLT (CFI) IN THE RIGHT FRONT SEAT & A STUDENT PLT/PROSPECTIVE BUYER IN THE LEFT FRONT SEAT. THE RWY ELEVATION WAS 2230 FT MSL AT THE SOUTH END & 2350 FT AT THE NORTH END. NORTH OF THE RWY, THE TERRAIN CONTINUED TO RISE & THE APPROACH END OF RWY 18 WAS OBSTRUCTED BY TREES UP TO 100 FT TALL. LANDINGS WERE PROHIBITED ON RWY 18 & ALL NIGHT OPERATIONS WERE PROHIBITED TO TRANSIENT PLTS. ACCORDING TO THE OPERATOR (ACFT), THE CFI SAID HE WAS AWARE OF THE OBSTRUCTIONS & LIMITATIONS & WAS FAMILIAR WITH THE ARPT. A WITNESS OBSERVED THE ACFT TOUCH DOWN AT NIGHT APRX 1/4 OF THE WAY DOWN THE RWY, THEN BOUNCE. THE ACFT DISAPPEARED FROM HIS VIEW, BUT SEVERAL WITNESSES HEARD WHAT THEY DESCRIBED AS APPLICATION OF FULL POWER. DURING A GO-AROUND, THE ACFT HIT THE TOPS OF THE TREES NEAR THE NORTH END OF THE RWY, THEN CRASHED & BURNED. ONE OF THE PASSENGERS WAS A PILOT & WAS A RESIDENT OF WEAVERVILLE, CA.