Physicists gave up on hadronic string theory ~ 1973 because
1. It has tachyons (unstable false pre-inflation vacuum without ODLRO)
2. It has a massless spin 2 particle
But 1. means spontaneous broken vacuum symmetries that provide massless Goldstone bosons that get eaten to make the Salam strong short range hadronic graviton explaining the Regge trajectories universal slope ~ 1/(1Gev)^2. String ~ Kerr blackhole G*^1/2 ~ 1 fermi.
In the case of spin 1 e.g. photon, one Goldstone boson needed to get 3 spin-1 polarizations.
So for spin 2 we need 3 Goldstone bosons to get the massive short-range hadronic graviton.
"If we knew what it was we were doing, it would not be called research, would it?"
- Albert Einstein