Since I worked at a warehouse that distributed and repaired Vitus bonded frames I have to say: yes there were failures. Most of them were on early Carbone frames (carbon fiber tubes, aluminum lugs). As Andy pointed out above, these were apparently due to galvanic corrosion at highly stressed joints, usually the bottom-bracket-to-seat-tube joint.

I'd guess that later frame designs suffered fewer failures because designers incorporated lessons learned from earlier failures. Factor in redesigned lugs, layers of insulating material between tube and lug, tighter tolerances, and better adhesives and bonding failures became unlikely.